{ "document": { "category": "csaf_base", "csaf_version": "2.0", "distribution": { "tlp": { "label": "WHITE" } }, "lang": "en", "notes": [ { "category": "legal_disclaimer", "text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this portal to enhance access to its information and vulnerabilities. The use of this information is subject to the following terms and conditions:\n\nThe vulnerabilities disclosed in this portal are gathered by NCSC-NL from a variety of open sources, which the user can retrieve from other platforms. NCSC-NL makes every reasonable effort to ensure that the content of this portal is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or real-time keeping up-to-date. NCSC-NL does not control nor guarantee the accuracy, relevance, timeliness or completeness of information obtained from these external sources. The vulnerabilities disclosed in this portal are intended solely for the convenience of professional parties to take appropriate measures to manage the risks posed to the cybersecurity. No rights can be derived from the information provided therein.\n\nNCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of the vulnerabilities disclosed in this portal. This includes damage resulting from the inaccuracy of incompleteness of the information contained in it.\nThe information on this page is subject to Dutch law. All disputes related to or arising from the use of this portal regarding the disclosure of vulnerabilities will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings." } ], "publisher": { "category": "coordinator", "contact_details": "cert@ncsc.nl", "name": "National Cyber Security Centre", "namespace": "https://www.ncsc.nl/" }, "title": "CVE-2026-33186", "tracking": { "current_release_date": "2026-04-03T00:32:39.889481Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-33186", "initial_release_date": "2026-03-18T20:44:18.637050Z", "revision_history": [ { "date": "2026-03-18T20:44:18.637050Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-03-18T20:44:29.750842Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-03-19T11:39:56.280250Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-03-20T22:39:08.230842Z", "number": "4", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (1).| CWES updated (1)." }, { "date": "2026-03-20T22:39:12.195642Z", "number": "5", "summary": "NCSC Score updated." }, { "date": "2026-03-20T23:25:36.033742Z", "number": "6", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (1).| CWES updated (1)." }, { "date": "2026-03-20T23:25:40.035030Z", "number": "7", "summary": "NCSC Score updated." }, { "date": "2026-03-21T15:23:10.682364Z", "number": "8", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-23T12:29:39.664634Z", "number": "9", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (1).| Product Identifiers created (1).| Product Remediations created (2).| Products created (1).| References created (3).| CWES updated (1).| Vendor_assessment created." }, { "date": "2026-03-23T12:29:48.460095Z", "number": "10", "summary": "NCSC Score updated." }, { "date": "2026-03-24T20:53:07.853893Z", "number": "11", "summary": "Unknown change." }, { "date": "2026-03-24T20:53:12.043426Z", "number": "12", "summary": "NCSC Score updated." }, { "date": "2026-03-25T18:42:09.600449Z", "number": "13", "summary": "References created (1)." }, { "date": "2026-03-25T18:42:12.357652Z", "number": "14", "summary": "NCSC Score updated." }, { "date": "2026-03-26T00:13:00.852108Z", "number": "15", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (2).| CWES updated (1)." }, { "date": "2026-03-26T00:13:08.020782Z", "number": "16", "summary": "NCSC Score updated." }, { "date": "2026-03-26T12:20:15.590384Z", "number": "17", "summary": "Source connected.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (2).| CWES updated (1)." }, { "date": "2026-03-26T12:20:17.831126Z", "number": "18", "summary": "NCSC Score updated." }, { "date": "2026-03-29T00:43:10.025848Z", "number": "19", "summary": "Source created.| CVE status created. (valid)| Description created for source.| Products created (2)." }, { "date": "2026-03-29T00:43:12.390984Z", "number": "20", "summary": "NCSC Score updated." }, { "date": "2026-03-29T03:16:23.857079Z", "number": "21", "summary": "References removed (1)." }, { "date": "2026-03-29T16:14:31.470622Z", "number": "22", "summary": "References created (1)." }, { "date": "2026-04-03T00:31:26.896894Z", "number": "23", "summary": "Source connected.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (8).| Product Remediations created (13).| Product Identifiers created (24).| Product Identifiers removed (24).| References created (16).| CWES updated (1)." }, { "date": "2026-04-03T00:31:38.059265Z", "number": "24", "summary": "NCSC Score updated." } ], "status": "interim", "version": "24" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:rpm/1.11", "product": { "name": "vers:rpm/1.11", "product_id": "CSAFPID-5986015", "product_identification_helper": { "cpe": "cpe:/a:redhat:network_observ_optr:1.11::el9" } } } ], "category": "product_name", "name": "Network Observability (NETOBSERV) 1.11.1" }, { "branches": [ { "category": "product_version_range", "name": "vers:oci/1773992622", "product": { "name": "vers:oci/1773992622", "product_id": "CSAFPID-5986016", "product_identification_helper": { "purl": "pkg:oci/network-observability-cli-rhel9@sha256%3Ab0f982a4b0cf36578c2483d9487e6c6f0343043737e01b6dd1b61778ed915e80?arch=ppc64le&repository_url=registry.redhat.io/network-observability&tag=1773992622" } } } ], "category": "product_name", "name": "network-observability-cli-rhel9" }, { "branches": [ { "category": "product_version_range", "name": "vers:oci/1774431392", "product": { "name": "vers:oci/1774431392", "product_id": "CSAFPID-5986020", "product_identification_helper": { "purl": "pkg:oci/network-observability-console-plugin-compat-rhel9@sha256%3A40512734417b0b3555046f6034e20dc9d834819bb83dbc2e6240bd656a4b2b3b?arch=amd64&repository_url=registry.redhat.io/network-observability&tag=1774431392" } } } ], "category": "product_name", "name": "network-observability-console-plugin-compat-rhel9" }, { "branches": [ { "category": "product_version_range", "name": "vers:oci/1774431617", "product": { "name": "vers:oci/1774431617", "product_id": "CSAFPID-5986021", "product_identification_helper": { "purl": "pkg:oci/network-observability-console-plugin-rhel9@sha256%3A51765514b5b6d1d205a26ad50893d11284256dd0afbd7603370c92242012973c?arch=s390x&repository_url=registry.redhat.io/network-observability&tag=1774431617" } } } ], "category": "product_name", "name": "network-observability-console-plugin-rhel9" }, { "branches": [ { "category": "product_version_range", "name": "vers:oci/1774887582", "product": { "name": "vers:oci/1774887582", "product_id": "CSAFPID-5986017", "product_identification_helper": { "purl": "pkg:oci/network-observability-ebpf-agent-rhel9@sha256%3Adc9c1e367526c7a2bae9694c253909f6716be82f89d1ceb9dc3a38528120d518?arch=arm64&repository_url=registry.redhat.io/network-observability&tag=1774887582" } } } ], "category": "product_name", "name": "network-observability-ebpf-agent-rhel9" }, { "branches": [ { "category": "product_version_range", "name": "vers:oci/1773997913", "product": { "name": "vers:oci/1773997913", "product_id": "CSAFPID-5986018", "product_identification_helper": { "purl": "pkg:oci/network-observability-flowlogs-pipeline-rhel9@sha256%3Aa72d7f075a569e1c0ba055ca748f04fa3c6ff889de498faba215174048b9b088?arch=s390x&repository_url=registry.redhat.io/network-observability&tag=1773997913" } } } ], "category": "product_name", "name": "network-observability-flowlogs-pipeline-rhel9" }, { "branches": [ { "category": "product_version_range", "name": "vers:oci/1774962696", "product": { "name": "vers:oci/1774962696", "product_id": "CSAFPID-5986022", "product_identification_helper": { "purl": "pkg:oci/network-observability-operator-bundle@sha256%3A325f2d9688ef540088f75b450d209fb8dd6b7b2dfc006f492f7575f3e8678607?arch=amd64&repository_url=registry.redhat.io/network-observability&tag=1774962696" } } } ], "category": "product_name", "name": "network-observability-operator-bundle" }, { "branches": [ { "category": "product_version_range", "name": "vers:oci/1774859742", "product": { "name": "vers:oci/1774859742", "product_id": "CSAFPID-5986019", "product_identification_helper": { "purl": "pkg:oci/network-observability-rhel9-operator@sha256%3Adc14db47fce0af17e02916369099477a584d52e113e20b47518007aa074b5453?arch=s390x&repository_url=registry.redhat.io/network-observability&tag=1774859742" } } } ], "category": "product_name", "name": "network-observability-rhel9-operator" } ], "category": "product_family", "name": "Network Observability (NETOBSERV)" }, { "branches": [ { "category": "product_version_range", "name": "vers:rpm/4", "product": { "name": "vers:rpm/4", "product_id": "CSAFPID-1439328", "product_identification_helper": { "cpe": "cpe:/a:redhat:openshift:4" } } } ], "category": "product_name", "name": "Red Hat OpenShift Container Platform 4" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:rpm/unknown", "product": { "name": "vers:rpm/unknown", "product_id": "CSAFPID-5891443" } } ], "category": "product_name", "name": "grpc" } ], "category": "product_family", "name": "Red Hat OpenShift Container Platform 4" } ], "category": "vendor", "name": "Red Hat" }, { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:microsoft/*", "product": { "name": "vers:microsoft/*", "product_id": "CSAFPID-5687142", "product_identification_helper": { "cpe": "cpe:2.3:a:microsoft:azl3_grpc_1.62.3-1:*:*:*:*:*:*:*:*" } } } ], "category": "product_name", "name": "azl3 grpc 1.62.3-1 on Azure Linux 3.0" }, { "branches": [ { "category": "product_version_range", "name": "vers:microsoft/*", "product": { "name": "vers:microsoft/*", "product_id": "CSAFPID-5687132", "product_identification_helper": { "cpe": "cpe:2.3:a:microsoft:cbl2_grpc_1.42.0-11:*:*:*:*:*:*:*:*" } } } ], "category": "product_name", "name": "cbl2 grpc 1.42.0-11 on CBL Mariner 2.0" } ], "category": "product_family", "name": "Mariner" } ], "category": "vendor", "name": "Microsoft" }, { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:deb/unknown", "product": { "name": "vers:deb/unknown", "product_id": "CSAFPID-5958927" } } ], "category": "product_name", "name": "golang-google-grpc" } ], "category": "product_family", "name": "bookworm" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:deb/unknown", "product": { "name": "vers:deb/unknown", "product_id": "CSAFPID-5958928" } } ], "category": "product_name", "name": "golang-google-grpc" } ], "category": "product_family", "name": "bullseye" } ], "category": "vendor", "name": "debian" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/>=0|<1.79.3", "product": { "name": "vers:unknown/>=0|<1.79.3", "product_id": "CSAFPID-5911163" } } ], "category": "product_name", "name": "grpc" }, { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<1.79.3", "product": { "name": "vers:unknown/<1.79.3", "product_id": "CSAFPID-5877658" } } ], "category": "product_name", "name": "grpc-go" } ], "category": "vendor", "name": "gRPC" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-33186", "cwe": { "id": "CWE-551", "name": "Incorrect Behavior Order: Authorization Before Parsing and Canonicalization" }, "flags": [ { "label": "vulnerable_code_not_present", "product_ids": [ "CSAFPID-5986020", "CSAFPID-5986021", "CSAFPID-5986022" ] } ], "notes": [ { "category": "description", "text": "### Impact\n_What kind of vulnerability is it? Who is impacted?_\n\nIt is an **Authorization Bypass** resulting from **Improper Input Validation** of the HTTP/2 `:path` pseudo-header.\n\nThe gRPC-Go server was too lenient in its routing logic, accepting requests where the `:path` omitted the mandatory leading slash (e.g., `Service/Method` instead of `/Service/Method`). While the server successfully routed these requests to the correct handler, authorization interceptors (including the official `grpc/authz` package) evaluated the raw, non-canonical path string. Consequently, \"deny\" rules defined using canonical paths (starting with `/`) failed to match the incoming request, allowing it to bypass the policy if a fallback \"allow\" rule was present.\n\n**Who is impacted?**\nThis affects gRPC-Go servers that meet both of the following criteria:\n1. They use path-based authorization interceptors, such as the official RBAC implementation in `google.golang.org/grpc/authz` or custom interceptors relying on `info.FullMethod` or `grpc.Method(ctx)`.\n2. Their security policy contains specific \"deny\" rules for canonical paths but allows other requests by default (a fallback \"allow\" rule).\n\nThe vulnerability is exploitable by an attacker who can send raw HTTP/2 frames with malformed `:path` headers directly to the gRPC server.\n\n### Patches\n_Has the problem been patched? What versions should users upgrade to?_\n\nYes, the issue has been patched. The fix ensures that any request with a `:path` that does not start with a leading slash is immediately rejected with a `codes.Unimplemented` error, preventing it from reaching authorization interceptors or handlers with a non-canonical path string.\n\nUsers should upgrade to the following versions (or newer):\n* **v1.79.3**\n* The latest **master** branch.\n\nIt is recommended that all users employing path-based authorization (especially `grpc/authz`) upgrade as soon as the patch is available in a tagged release.\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\n\nWhile upgrading is the most secure and recommended path, users can mitigate the vulnerability using one of the following methods:\n\n#### 1. Use a Validating Interceptor (Recommended Mitigation)\nAdd an \"outermost\" interceptor to your server that validates the path before any other authorization logic runs:\n\n```go\nfunc pathValidationInterceptor(ctx context.Context, req any, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (any, error) {\n if info.FullMethod == \"\" || info.FullMethod[0] != '/' {\n return nil, status.Errorf(codes.Unimplemented, \"malformed method name\")\n } \n return handler(ctx, req)\n}\n\n// Ensure this is the FIRST interceptor in your chain\ns := grpc.NewServer(\n grpc.ChainUnaryInterceptor(pathValidationInterceptor, authzInterceptor),\n)\n```\n\n#### 2. Infrastructure-Level Normalization\nIf your gRPC server is behind a reverse proxy or load balancer (such as Envoy, NGINX, or an L7 Cloud Load Balancer), ensure it is configured to enforce strict HTTP/2 compliance for pseudo-headers and reject or normalize requests where the `:path` header does not start with a leading slash.\n\n#### 3. Policy Hardening\nSwitch to a \"default deny\" posture in your authorization policies (explicitly listing all allowed paths and denying everything else) to reduce the risk of bypasses via malformed inputs.", "title": "github - https://github.com/advisories/GHSA-p77j-4mvh-x3m3" }, { "category": "description", "text": "### Impact\n_What kind of vulnerability is it? Who is impacted?_\n\nIt is an **Authorization Bypass** resulting from **Improper Input Validation** of the HTTP/2 `:path` pseudo-header.\n\nThe gRPC-Go server was too lenient in its routing logic, accepting requests where the `:path` omitted the mandatory leading slash (e.g., `Service/Method` instead of `/Service/Method`). While the server successfully routed these requests to the correct handler, authorization interceptors (including the official `grpc/authz` package) evaluated the raw, non-canonical path string. Consequently, \"deny\" rules defined using canonical paths (starting with `/`) failed to match the incoming request, allowing it to bypass the policy if a fallback \"allow\" rule was present.\n\n**Who is impacted?**\nThis affects gRPC-Go servers that meet both of the following criteria:\n1. They use path-based authorization interceptors, such as the official RBAC implementation in `google.golang.org/grpc/authz` or custom interceptors relying on `info.FullMethod` or `grpc.Method(ctx)`.\n2. Their security policy contains specific \"deny\" rules for canonical paths but allows other requests by default (a fallback \"allow\" rule).\n\nThe vulnerability is exploitable by an attacker who can send raw HTTP/2 frames with malformed `:path` headers directly to the gRPC server.\n\n### Patches\n_Has the problem been patched? What versions should users upgrade to?_\n\nYes, the issue has been patched. The fix ensures that any request with a `:path` that does not start with a leading slash is immediately rejected with a `codes.Unimplemented` error, preventing it from reaching authorization interceptors or handlers with a non-canonical path string.\n\nUsers should upgrade to the following versions (or newer):\n* **v1.79.3**\n* The latest **master** branch.\n\nIt is recommended that all users employing path-based authorization (especially `grpc/authz`) upgrade as soon as the patch is available in a tagged release.\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\n\nWhile upgrading is the most secure and recommended path, users can mitigate the vulnerability using one of the following methods:\n\n#### 1. Use a Validating Interceptor (Recommended Mitigation)\nAdd an \"outermost\" interceptor to your server that validates the path before any other authorization logic runs:\n\n```go\nfunc pathValidationInterceptor(ctx context.Context, req any, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (any, error) {\n if info.FullMethod == \"\" || info.FullMethod[0] != '/' {\n return nil, status.Errorf(codes.Unimplemented, \"malformed method name\")\n } \n return handler(ctx, req)\n}\n\n// Ensure this is the FIRST interceptor in your chain\ns := grpc.NewServer(\n grpc.ChainUnaryInterceptor(pathValidationInterceptor, authzInterceptor),\n)\n```\n\n#### 2. Infrastructure-Level Normalization\nIf your gRPC server is behind a reverse proxy or load balancer (such as Envoy, NGINX, or an L7 Cloud Load Balancer), ensure it is configured to enforce strict HTTP/2 compliance for pseudo-headers and reject or normalize requests where the `:path` header does not start with a leading slash.\n\n#### 3. Policy Hardening\nSwitch to a \"default deny\" posture in your authorization policies (explicitly listing all allowed paths and denying everything else) to reduce the risk of bypasses via malformed inputs.", "title": "github - https://api.github.com/advisories/GHSA-p77j-4mvh-x3m3" }, { "category": "description", "text": "gRPC-Go is the Go language implementation of gRPC. Versions prior to 1.79.3 have an authorization bypass resulting from improper input validation of the HTTP/2 `:path` pseudo-header. The gRPC-Go server was too lenient in its routing logic, accepting requests where the `:path` omitted the mandatory leading slash (e.g., `Service/Method` instead of `/Service/Method`). While the server successfully routed these requests to the correct handler, authorization interceptors (including the official `grpc/authz` package) evaluated the raw, non-canonical path string. Consequently, \"deny\" rules defined using canonical paths (starting with `/`) failed to match the incoming request, allowing it to bypass the policy if a fallback \"allow\" rule was present. This affects gRPC-Go servers that use path-based authorization interceptors, such as the official RBAC implementation in `google.golang.org/grpc/authz` or custom interceptors relying on `info.FullMethod` or `grpc.Method(ctx)`; AND that have a security policy contains specific \"deny\" rules for canonical paths but allows other requests by default (a fallback \"allow\" rule). The vulnerability is exploitable by an attacker who can send raw HTTP/2 frames with malformed `:path` headers directly to the gRPC server. The fix in version 1.79.3 ensures that any request with a `:path` that does not start with a leading slash is immediately rejected with a `codes.Unimplemented` error, preventing it from reaching authorization interceptors or handlers with a non-canonical path string. While upgrading is the most secure and recommended path, users can mitigate the vulnerability using one of the following methods: Use a validating interceptor (recommended mitigation); infrastructure-level normalization; and/or policy hardening.", "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33186.json" }, { "category": "description", "text": "gRPC-Go is the Go language implementation of gRPC. Versions prior to 1.79.3 have an authorization bypass resulting from improper input validation of the HTTP/2 `:path` pseudo-header. The gRPC-Go server was too lenient in its routing logic, accepting requests where the `:path` omitted the mandatory leading slash (e.g., `Service/Method` instead of `/Service/Method`). While the server successfully routed these requests to the correct handler, authorization interceptors (including the official `grpc/authz` package) evaluated the raw, non-canonical path string. Consequently, \"deny\" rules defined using canonical paths (starting with `/`) failed to match the incoming request, allowing it to bypass the policy if a fallback \"allow\" rule was present. This affects gRPC-Go servers that use path-based authorization interceptors, such as the official RBAC implementation in `google.golang.org/grpc/authz` or custom interceptors relying on `info.FullMethod` or `grpc.Method(ctx)`; AND that have a security policy contains specific \"deny\" rules for canonical paths but allows other requests by default (a fallback \"allow\" rule). The vulnerability is exploitable by an attacker who can send raw HTTP/2 frames with malformed `:path` headers directly to the gRPC server. The fix in version 1.79.3 ensures that any request with a `:path` that does not start with a leading slash is immediately rejected with a `codes.Unimplemented` error, preventing it from reaching authorization interceptors or handlers with a non-canonical path string. While upgrading is the most secure and recommended path, users can mitigate the vulnerability using one of the following methods: Use a validating interceptor (recommended mitigation); infrastructure-level normalization; and/or policy hardening.", "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33186" }, { "category": "description", "text": "A flaw was found in gRPC-Go, the Go language implementation of gRPC. This vulnerability, an authorization bypass, is caused by improper input validation of the HTTP/2 `:path` pseudo-header. A remote attacker can exploit this by sending raw HTTP/2 frames with a malformed `:path` that omits the mandatory leading slash. This allows the attacker to bypass defined security policies, potentially leading to unauthorized access to services or information disclosure.", "title": "redhat - https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-33186.json" }, { "category": "description", "text": "### Impact\n_What kind of vulnerability is it? Who is impacted?_\n\nIt is an **Authorization Bypass** resulting from **Improper Input Validation** of the HTTP/2 `:path` pseudo-header.\n\nThe gRPC-Go server was too lenient in its routing logic, accepting requests where the `:path` omitted the mandatory leading slash (e.g., `Service/Method` instead of `/Service/Method`). While the server successfully routed these requests to the correct handler, authorization interceptors (including the official `grpc/authz` package) evaluated the raw, non-canonical path string. Consequently, \"deny\" rules defined using canonical paths (starting with `/`) failed to match the incoming request, allowing it to bypass the policy if a fallback \"allow\" rule was present.\n\n**Who is impacted?**\nThis affects gRPC-Go servers that meet both of the following criteria:\n1. They use path-based authorization interceptors, such as the official RBAC implementation in `google.golang.org/grpc/authz` or custom interceptors relying on `info.FullMethod` or `grpc.Method(ctx)`.\n2. Their security policy contains specific \"deny\" rules for canonical paths but allows other requests by default (a fallback \"allow\" rule).\n\nThe vulnerability is exploitable by an attacker who can send raw HTTP/2 frames with malformed `:path` headers directly to the gRPC server.\n\n### Patches\n_Has the problem been patched? What versions should users upgrade to?_\n\nYes, the issue has been patched. The fix ensures that any request with a `:path` that does not start with a leading slash is immediately rejected with a `codes.Unimplemented` error, preventing it from reaching authorization interceptors or handlers with a non-canonical path string.\n\nUsers should upgrade to the following versions (or newer):\n* **v1.79.3**\n* The latest **master** branch.\n\nIt is recommended that all users employing path-based authorization (especially `grpc/authz`) upgrade as soon as the patch is available in a tagged release.\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\n\nWhile upgrading is the most secure and recommended path, users can mitigate the vulnerability using one of the following methods:\n\n#### 1. Use a Validating Interceptor (Recommended Mitigation)\nAdd an \"outermost\" interceptor to your server that validates the path before any other authorization logic runs:\n\n```go\nfunc pathValidationInterceptor(ctx context.Context, req any, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (any, error) {\n if info.FullMethod == \"\" || info.FullMethod[0] != '/' {\n return nil, status.Errorf(codes.Unimplemented, \"malformed method name\")\n } \n return handler(ctx, req)\n}\n\n// Ensure this is the FIRST interceptor in your chain\ns := grpc.NewServer(\n grpc.ChainUnaryInterceptor(pathValidationInterceptor, authzInterceptor),\n)\n```\n\n#### 2. Infrastructure-Level Normalization\nIf your gRPC server is behind a reverse proxy or load balancer (such as Envoy, NGINX, or an L7 Cloud Load Balancer), ensure it is configured to enforce strict HTTP/2 compliance for pseudo-headers and reject or normalize requests where the `:path` header does not start with a leading slash.\n\n#### 3. Policy Hardening\nSwitch to a \"default deny\" posture in your authorization policies (explicitly listing all allowed paths and denying everything else) to reduce the risk of bypasses via malformed inputs.", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGHSA-p77j-4mvh-x3m3.json?alt=media" }, { "category": "description", "text": "gRPC-Go has an authorization bypass via missing leading slash in :path", "title": "microsoft - https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2026-Mar" }, { "category": "description", "text": "gRPC-Go is the Go language implementation of gRPC. Versions prior to 1.79.3 have an authorization bypass resulting from improper input validation of the HTTP/2 `:path` pseudo-header. The gRPC-Go server was too lenient in its routing logic, accepting requests where the `:path` omitted the mandatory leading slash (e.g., `Service/Method` instead of `/Service/Method`). While the server successfully routed these requests to the correct handler, authorization interceptors (including the official `grpc/authz` package) evaluated the raw, non-canonical path string. Consequently, \"deny\" rules defined using canonical paths (starting with `/`) failed to match the incoming request, allowing it to bypass the policy if a fallback \"allow\" rule was present. This affects gRPC-Go servers that use path-based authorization interceptors, such as the official RBAC implementation in `google.golang.org/grpc/authz` or custom interceptors relying on `info.FullMethod` or `grpc.Method(ctx)`; AND that have a security policy contains specific \"deny\" rules for canonical paths but allows other requests by default (a fallback \"allow\" rule). The vulnerability is exploitable by an attacker who can send raw HTTP/2 frames with malformed `:path` headers directly to the gRPC server. The fix in version 1.79.3 ensures that any request with a `:path` that does not start with a leading slash is immediately rejected with a `codes.Unimplemented` error, preventing it from reaching authorization interceptors or handlers with a non-canonical path string. While upgrading is the most secure and recommended path, users can mitigate the vulnerability using one of the following methods: Use a validating interceptor (recommended mitigation); infrastructure-level normalization; and/or policy hardening.", "title": "debian - https://security-tracker.debian.org/tracker/CVE-2026-33186" }, { "category": "description", "text": "A flaw was found in gRPC-Go, the Go language implementation of gRPC. This vulnerability, an authorization bypass, is caused by improper input validation of the HTTP/2 `:path` pseudo-header. A remote attacker can exploit this by sending raw HTTP/2 frames with a malformed `:path` that omits the mandatory leading slash. This allows the attacker to bypass defined security policies, potentially leading to unauthorized access to services or information disclosure.", "title": "redhat - https://access.redhat.com/hydra/rest/securitydata/csaf/RHSA-2026:6428.json" }, { "category": "other", "text": "0.00013", "title": "EPSS" }, { "category": "other", "text": "4.2", "title": "NCSC Score" }, { "category": "other", "text": "VENDOR FIX as product remediation category", "title": "NCSC Score top increasing factors" }, { "category": "other", "text": "There is cwe data available from source Nvd, Is related to (a version of) an uncommon product, The value of the most recent EPSS score", "title": "NCSC Score top decreasing factors" }, { "category": "details", "text": "Severity: 3\n", "title": "Vendor assessment" } ], "product_status": { "fixed": [ "CSAFPID-5986016", "CSAFPID-5986017", "CSAFPID-5986018", "CSAFPID-5986019" ], "known_affected": [ "CSAFPID-5877658", "CSAFPID-1439328", "CSAFPID-5891443", "CSAFPID-5911163", "CSAFPID-5687132", "CSAFPID-5687142", "CSAFPID-5958927", "CSAFPID-5958928" ], "known_not_affected": [ "CSAFPID-5986020", "CSAFPID-5986021", "CSAFPID-5986022" ] }, "references": [ { "category": "external", "summary": "Source - github", "url": "https://github.com/advisories/GHSA-p77j-4mvh-x3m3" }, { "category": "external", "summary": "Source raw - github", "url": "https://api.github.com/advisories/GHSA-p77j-4mvh-x3m3" }, { "category": "external", "summary": "Source - github", "url": "https://api.github.com/advisories/GHSA-p77j-4mvh-x3m3" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33186.json" }, { "category": "external", "summary": "Source - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33186" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Source - redhat", "url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-33186.json" }, { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGHSA-p77j-4mvh-x3m3.json?alt=media" }, { "category": "external", "summary": "Source - microsoft", "url": "https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2026-Mar" }, { "category": "external", "summary": "Source - debian", "url": "https://security-tracker.debian.org/tracker/CVE-2026-33186" }, { "category": "external", "summary": "Source - redhat", "url": "https://access.redhat.com/hydra/rest/securitydata/csaf/RHSA-2026:6428.json" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd; osv; redhat", "url": "https://github.com/grpc/grpc-go/security/advisories/GHSA-p77j-4mvh-x3m3" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/advisories/GHSA-p77j-4mvh-x3m3" }, { "category": "external", "summary": "Reference - redhat", "url": "https://www.cve.org/CVERecord?id=CVE-2026-33186" }, { "category": "external", "summary": "Reference - github; osv; redhat", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33186" }, { "category": "external", "summary": "Reference - redhat", "url": "https://access.redhat.com/security/cve/CVE-2026-33186" }, { "category": "external", "summary": "Reference - redhat", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2449833" }, { "category": "external", "summary": "Reference - redhat", "url": "https://access.redhat.com/errata/RHSA-2026:6428" }, { "category": "external", "summary": "Reference - redhat", "url": "https://access.redhat.com/security/cve/CVE-2025-61726" }, { "category": "external", "summary": "Reference - redhat", "url": "https://access.redhat.com/security/cve/CVE-2025-61728" }, { "category": "external", "summary": "Reference - redhat", "url": "https://access.redhat.com/security/cve/CVE-2025-61729" }, { "category": "external", "summary": "Reference - redhat", "url": "https://access.redhat.com/security/cve/CVE-2025-68121" }, { "category": "external", "summary": "Reference - redhat", "url": "https://access.redhat.com/security/cve/CVE-2026-25639" }, { "category": "external", "summary": "Reference - redhat", "url": "https://access.redhat.com/security/cve/CVE-2026-26960" }, { "category": "external", "summary": "Reference - redhat", "url": "https://access.redhat.com/security/cve/CVE-2026-29063" }, { "category": "external", "summary": "Reference - redhat", "url": "https://access.redhat.com/security/updates/classification/" }, { "category": "external", "summary": "Reference - redhat", "url": "https://docs.openshift.com/container-platform/latest/observability/network_observability/network-observability-operator-release-notes.html" }, { "category": "external", "summary": "Reference - redhat", "url": "https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_6428.json" } ], "remediations": [ { "category": "mitigation", "details": "To mitigate this issue, implement infrastructure-level normalization to ensure all incoming HTTP/2 `:path` headers are properly formatted with a leading slash before reaching the gRPC-Go server. This can be achieved by configuring a reverse proxy or API gateway to validate and normalize the `:path` header. Ensure that any such intermediary is properly configured and restarted to apply the changes, which may temporarily impact service availability.", "product_ids": [ "CSAFPID-1439328", "CSAFPID-5891443" ] }, { "category": "vendor_fix", "details": "For details on how to apply this update, refer to:\n\nhttps://access.redhat.com/articles/11258", "product_ids": [ "CSAFPID-5986015", "CSAFPID-5986016", "CSAFPID-5986017", "CSAFPID-5986018", "CSAFPID-5986019" ], "restart_required": { "category": "none" }, "url": "https://access.redhat.com/errata/RHSA-2026:6428" }, { "category": "workaround", "details": "To mitigate this issue, implement infrastructure-level normalization to ensure all incoming HTTP/2 `:path` headers are properly formatted with a leading slash before reaching the gRPC-Go server. This can be achieved by configuring a reverse proxy or API gateway to validate and normalize the `:path` header. Ensure that any such intermediary is properly configured and restarted to apply the changes, which may temporarily impact service availability.", "product_ids": [ "CSAFPID-5986015", "CSAFPID-5986016", "CSAFPID-5986017", "CSAFPID-5986018", "CSAFPID-5986019", "CSAFPID-5986020", "CSAFPID-5986021", "CSAFPID-5986022" ] } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N", "baseScore": 9.1, "baseSeverity": "CRITICAL" }, "products": [ "CSAFPID-1439328", "CSAFPID-5687132", "CSAFPID-5687142", "CSAFPID-5877658", "CSAFPID-5891443", "CSAFPID-5911163", "CSAFPID-5958927", "CSAFPID-5958928" ] } ], "title": "CVE-2026-33186" } ] }