{ "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-2026-26308", "tracking": { "current_release_date": "2026-03-27T09:06:33.581301Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-26308", "initial_release_date": "2026-03-10T19:19:10.767379Z", "revision_history": [ { "date": "2026-03-10T19:19:10.767379Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-03-10T19:19:14.971807Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-03-10T19:38:52.791600Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (4).| References created (2).| CWES updated (1)." }, { "date": "2026-03-10T19:38:57.903071Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-03-10T21:27:53.865230Z", "number": "5", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-03-10T21:27:56.587796Z", "number": "6", "summary": "NCSC Score updated." }, { "date": "2026-03-10T21:39:51.181479Z", "number": "7", "summary": "Unknown change." }, { "date": "2026-03-10T22:43:06.482172Z", "number": "8", "summary": "References created (2).| CWES updated (1)." }, { "date": "2026-03-11T00:13:53.175409Z", "number": "9", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (4).| Product Identifiers created (1).| References created (1).| CWES updated (1)." }, { "date": "2026-03-11T15:00:51.835871Z", "number": "10", "summary": "Source created.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-11T15:00:53.745393Z", "number": "11", "summary": "NCSC Score updated." }, { "date": "2026-03-11T16:26:31.757593Z", "number": "12", "summary": "Products connected (3).| Product Identifiers created (4).| Products created (1).| Exploits created (1)." }, { "date": "2026-03-11T16:26:36.962754Z", "number": "13", "summary": "NCSC Score updated." }, { "date": "2026-03-12T12:16:21.241204Z", "number": "14", "summary": "Source created.| CVE status created. (valid)| Products created (5).| Product Identifiers created (2).| References created (4)." }, { "date": "2026-03-12T12:16:24.003489Z", "number": "15", "summary": "NCSC Score updated." }, { "date": "2026-03-19T15:29:53.153482Z", "number": "16", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (4).| CWES updated (1)." }, { "date": "2026-03-19T15:29:55.633493Z", "number": "17", "summary": "NCSC Score updated." }, { "date": "2026-03-20T09:44:05.794309Z", "number": "18", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-20T09:44:09.616176Z", "number": "19", "summary": "NCSC Score updated." }, { "date": "2026-03-27T09:06:31.352904Z", "number": "20", "summary": "Products connected (1).| Product Identifiers created (1).| References created (3)." } ], "status": "interim", "version": "20" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/envoy proxy", "product": { "name": "vers:unknown/envoy proxy", "product_id": "CSAFPID-5810304", "product_identification_helper": { "cpe": "cpe:/a:google:cloud_platform:envoy_proxy" } } }, { "category": "product_version_range", "name": "vers:unknown/istio", "product": { "name": "vers:unknown/istio", "product_id": "CSAFPID-5810308", "product_identification_helper": { "cpe": "cpe:/a:google:cloud_platform:istio" } } }, { "category": "product_version_range", "name": "vers:unknown/service mesh <1.26.8-asm.3", "product": { "name": "vers:unknown/service mesh <1.26.8-asm.3", "product_id": "CSAFPID-5810305" } }, { "category": "product_version_range", "name": "vers:unknown/service mesh <1.27.8-asm.7", "product": { "name": "vers:unknown/service mesh <1.27.8-asm.7", "product_id": "CSAFPID-5810307" } }, { "category": "product_version_range", "name": "vers:unknown/service mesh <1.28.5-asm.9", "product": { "name": "vers:unknown/service mesh <1.28.5-asm.9", "product_id": "CSAFPID-5810306" } } ], "category": "product_name", "name": "Cloud Platform" } ], "category": "vendor", "name": "Google" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/1.37.0", "product": { "name": "vers:unknown/1.37.0", "product_id": "CSAFPID-5780406", "product_identification_helper": { "cpe": "cpe:2.3:a:envoyproxy:envoy:1.37.0:*:*:*:*:*:*:*", "purl": "pkg:golang/github.com/envoyproxy/envoy@1.37.0" } } }, { "category": "product_version_range", "name": "vers:unknown/<1.34.13", "product": { "name": "vers:unknown/<1.34.13", "product_id": "CSAFPID-5777010", "product_identification_helper": { "cpe": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*" } } }, { "category": "product_version_range", "name": "vers:unknown/>=0|<=1.34.12", "product": { "name": "vers:unknown/>=0|<=1.34.12", "product_id": "CSAFPID-5780409" } }, { "category": "product_version_range", "name": "vers:unknown/>=1.35.0|<1.35.8", "product": { "name": "vers:unknown/>=1.35.0|<1.35.8", "product_id": "CSAFPID-5795752", "product_identification_helper": { "cpe": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*" } } }, { "category": "product_version_range", "name": "vers:unknown/>=1.35.0|<1.35.9", "product": { "name": "vers:unknown/>=1.35.0|<1.35.9", "product_id": "CSAFPID-5777009" } }, { "category": "product_version_range", "name": "vers:unknown/>=1.35.0|<=1.35.8", "product": { "name": "vers:unknown/>=1.35.0|<=1.35.8", "product_id": "CSAFPID-5780408" } }, { "category": "product_version_range", "name": "vers:unknown/>=1.36.0|<1.36.5", "product": { "name": "vers:unknown/>=1.36.0|<1.36.5", "product_id": "CSAFPID-5777008", "product_identification_helper": { "cpe": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*" } } }, { "category": "product_version_range", "name": "vers:unknown/>=1.36.0|<=1.36.4", "product": { "name": "vers:unknown/>=1.36.0|<=1.36.4", "product_id": "CSAFPID-5780407" } }, { "category": "product_version_range", "name": "vers:unknown/>=1.37.0|<1.37.1", "product": { "name": "vers:unknown/>=1.37.0|<1.37.1", "product_id": "CSAFPID-5777007" } } ], "category": "product_name", "name": "Envoy" } ], "category": "vendor", "name": "Envoy Proxy" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/unknown", "product": { "name": "vers:unknown/unknown", "product_id": "CSAFPID-1317175", "product_identification_helper": { "cpe": "cpe:/o:redhat:enterprise_linux:-" } } } ], "category": "product_name", "name": "Red Hat Enterprise Linux" } ], "category": "vendor", "name": "Red Hat" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-26308", "cwe": { "id": "CWE-863", "name": "Incorrect Authorization" }, "notes": [ { "category": "description", "text": "## 1. Summary\nThe Envoy RBAC (Role-Based Access Control) filter contains a logic vulnerability in how it validates HTTP headers when multiple values are present for the same header name. Instead of validating each header value individually, Envoy concatenates all values into a single comma-separated string. This behavior allows attackers to bypass RBAC policies—specifically \"Deny\" rules—by sending duplicate headers, effectively obscuring the malicious value from exact-match mechanisms.\n\n## 2. Attack Scenario\nConsider an environment where an administrator wants to block external access to internal resources using a specific header flag.\n\n### Configuration\nThe Envoy proxy is configured with a **Deny** rule to reject requests containing the header `internal: true`.\n* **Rule Type:** Exact Match\n* **Target:** `internal` header must not equal `true`.\n\n### The Bypass Logic\n1. **Standard Request (Blocked):**\n * **Input:** `internal: true`\n * **Envoy Processing:** Sees string `\"true\"`.\n * **Result:** Match found. **Request Denied.**\n\n2. **Exploit Request (Bypassed):**\n * **Input:**\n ```http\n internal: true\n internal: true\n ```\n * **Envoy Processing:** Concatenates values into `\"true,true\"`.\n * **Matcher Evaluation:** Does `\"true,true\"` equal `\"true\"`? **No.**\n * **Result:** The Deny rule fails to trigger. **Request Allowed.**\n\n## 3. Implications\n* **RBAC Bypass:** Remote attackers can bypass configured access controls.\n* **Unauthorized Access:** Sensitive internal resources or administrative endpoints protected by header-based Deny rules become accessible.\n* **Risk:** High, particularly for deployments relying on \"Exact Match\" strategies for security blocking.\n\n## 4. Reproduction Steps\nTo verify this vulnerability:\n\n1. **Deploy Envoy:** Configure an instance with an RBAC **Deny** rule that performs an **exact match** on a specific header (e.g., `internal: true`).\n2. **Baseline Test:** Send a request containing the header `internal: true`.\n * *Observation:* Envoy blocks this request (HTTP 403).\n3. **Exploit Test:** Send a second request containing the same header twice:\n ```http\n GET /restricted-resource HTTP/1.1\n Host: example.com\n internal: true\n internal: true\n ```\n * *Observation:* Envoy allows the request, granting access to the resource.\n\n## 6. Recommendations\n**Fix Header Validation Logic:**\nModify the RBAC filter to validate each header value instance individually. Avoid relying on the concatenated string output of `getAllOfHeaderAsString()` for security-critical matching unless the matcher is explicitly designed to parse comma-separated lists.\n\n** Examine the DENY role to use a Regex style fix.\n\n**Credit:** Dor Konis", "title": "github - https://github.com/advisories/GHSA-ghc4-35x6-crw5" }, { "category": "description", "text": "Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, the Envoy RBAC (Role-Based Access Control) filter contains a logic vulnerability in how it validates HTTP headers when multiple values are present for the same header name. Instead of validating each header value individually, Envoy concatenates all values into a single comma-separated string. This behavior allows attackers to bypass RBAC policies—specifically \"Deny\" rules—by sending duplicate headers, effectively obscuring the malicious value from exact-match mechanisms. This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.", "title": "cveprojectv5 - https://www.cve.org/CVERecord?id=CVE-2026-26308" }, { "category": "description", "text": "Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, the Envoy RBAC (Role-Based Access Control) filter contains a logic vulnerability in how it validates HTTP headers when multiple values are present for the same header name. Instead of validating each header value individually, Envoy concatenates all values into a single comma-separated string. This behavior allows attackers to bypass RBAC policies—specifically \"Deny\" rules—by sending duplicate headers, effectively obscuring the malicious value from exact-match mechanisms. This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.", "title": "nvd - https://nvd.nist.gov/vuln/detail/CVE-2026-26308" }, { "category": "description", "text": "## 1. Summary\nThe Envoy RBAC (Role-Based Access Control) filter contains a logic vulnerability in how it validates HTTP headers when multiple values are present for the same header name. Instead of validating each header value individually, Envoy concatenates all values into a single comma-separated string. This behavior allows attackers to bypass RBAC policies—specifically \"Deny\" rules—by sending duplicate headers, effectively obscuring the malicious value from exact-match mechanisms.\n\n## 2. Attack Scenario\nConsider an environment where an administrator wants to block external access to internal resources using a specific header flag.\n\n### Configuration\nThe Envoy proxy is configured with a **Deny** rule to reject requests containing the header `internal: true`.\n* **Rule Type:** Exact Match\n* **Target:** `internal` header must not equal `true`.\n\n### The Bypass Logic\n1. **Standard Request (Blocked):**\n * **Input:** `internal: true`\n * **Envoy Processing:** Sees string `\"true\"`.\n * **Result:** Match found. **Request Denied.**\n\n2. **Exploit Request (Bypassed):**\n * **Input:**\n ```http\n internal: true\n internal: true\n ```\n * **Envoy Processing:** Concatenates values into `\"true,true\"`.\n * **Matcher Evaluation:** Does `\"true,true\"` equal `\"true\"`? **No.**\n * **Result:** The Deny rule fails to trigger. **Request Allowed.**\n\n## 3. Implications\n* **RBAC Bypass:** Remote attackers can bypass configured access controls.\n* **Unauthorized Access:** Sensitive internal resources or administrative endpoints protected by header-based Deny rules become accessible.\n* **Risk:** High, particularly for deployments relying on \"Exact Match\" strategies for security blocking.\n\n## 4. Reproduction Steps\nTo verify this vulnerability:\n\n1. **Deploy Envoy:** Configure an instance with an RBAC **Deny** rule that performs an **exact match** on a specific header (e.g., `internal: true`).\n2. **Baseline Test:** Send a request containing the header `internal: true`.\n * *Observation:* Envoy blocks this request (HTTP 403).\n3. **Exploit Test:** Send a second request containing the same header twice:\n ```http\n GET /restricted-resource HTTP/1.1\n Host: example.com\n internal: true\n internal: true\n ```\n * *Observation:* Envoy allows the request, granting access to the resource.\n\n## 6. Recommendations\n**Fix Header Validation Logic:**\nModify the RBAC filter to validate each header value instance individually. Avoid relying on the concatenated string output of `getAllOfHeaderAsString()` for security-critical matching unless the matcher is explicitly designed to parse comma-separated lists.\n\n** Examine the DENY role to use a Regex style fix.\n\n**Credit:** Dor Konis", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGHSA-ghc4-35x6-crw5.json?alt=media" }, { "category": "description", "text": "## 1. Summary\nThe Envoy RBAC (Role-Based Access Control) filter contains a logic vulnerability in how it validates HTTP headers when multiple values are present for the same header name. Instead of validating each header value individually, Envoy concatenates all values into a single comma-separated string. This behavior allows attackers to bypass RBAC policies—specifically \"Deny\" rules—by sending duplicate headers, effectively obscuring the malicious value from exact-match mechanisms.\n\n## 2. Attack Scenario\nConsider an environment where an administrator wants to block external access to internal resources using a specific header flag.\n\n### Configuration\nThe Envoy proxy is configured with a **Deny** rule to reject requests containing the header `internal: true`.\n* **Rule Type:** Exact Match\n* **Target:** `internal` header must not equal `true`.\n\n### The Bypass Logic\n1. **Standard Request (Blocked):**\n * **Input:** `internal: true`\n * **Envoy Processing:** Sees string `\"true\"`.\n * **Result:** Match found. **Request Denied.**\n\n2. **Exploit Request (Bypassed):**\n * **Input:**\n ```http\n internal: true\n internal: true\n ```\n * **Envoy Processing:** Concatenates values into `\"true,true\"`.\n * **Matcher Evaluation:** Does `\"true,true\"` equal `\"true\"`? **No.**\n * **Result:** The Deny rule fails to trigger. **Request Allowed.**\n\n## 3. Implications\n* **RBAC Bypass:** Remote attackers can bypass configured access controls.\n* **Unauthorized Access:** Sensitive internal resources or administrative endpoints protected by header-based Deny rules become accessible.\n* **Risk:** High, particularly for deployments relying on \"Exact Match\" strategies for security blocking.\n\n## 4. Reproduction Steps\nTo verify this vulnerability:\n\n1. **Deploy Envoy:** Configure an instance with an RBAC **Deny** rule that performs an **exact match** on a specific header (e.g., `internal: true`).\n2. **Baseline Test:** Send a request containing the header `internal: true`.\n * *Observation:* Envoy blocks this request (HTTP 403).\n3. **Exploit Test:** Send a second request containing the same header twice:\n ```http\n GET /restricted-resource HTTP/1.1\n Host: example.com\n internal: true\n internal: true\n ```\n * *Observation:* Envoy allows the request, granting access to the resource.\n\n## 6. Recommendations\n**Fix Header Validation Logic:**\nModify the RBAC filter to validate each header value instance individually. Avoid relying on the concatenated string output of `getAllOfHeaderAsString()` for security-critical matching unless the matcher is explicitly designed to parse comma-separated lists.\n\n** Examine the DENY role to use a Regex style fix.\n\n**Credit:** Dor Konis", "title": "github - https://api.github.com/advisories/GHSA-ghc4-35x6-crw5" }, { "category": "other", "text": "3e-05", "title": "EPSS" }, { "category": "other", "text": "4.3", "title": "NCSC Score" }, { "category": "other", "text": "There is product data available from source Certbundde", "title": "NCSC Score top increasing factors" }, { "category": "other", "text": "There is exploit data available from source Nvd, Is related to (a version of) an uncommon product", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5777007", "CSAFPID-5777008", "CSAFPID-5777009", "CSAFPID-5777010", "CSAFPID-5780406", "CSAFPID-5780407", "CSAFPID-5780408", "CSAFPID-5780409", "CSAFPID-5795752", "CSAFPID-5810304", "CSAFPID-5810305", "CSAFPID-5810306", "CSAFPID-5810307", "CSAFPID-5810308", "CSAFPID-1317175" ] }, "references": [ { "category": "external", "summary": "Source - github", "url": "https://github.com/advisories/GHSA-ghc4-35x6-crw5" }, { "category": "external", "summary": "Source raw - github", "url": "https://api.github.com/advisories/GHSA-ghc4-35x6-crw5" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://www.cve.org/CVERecord?id=CVE-2026-26308" }, { "category": "external", "summary": "Source raw - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/26xxx/CVE-2026-26308.json" }, { "category": "external", "summary": "Source - nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26308" }, { "category": "external", "summary": "Source raw - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-26308" }, { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGHSA-ghc4-35x6-crw5.json?alt=media" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-26308" }, { "category": "external", "summary": "Source raw - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Source - certbundde", "url": "https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-0704.json" }, { "category": "external", "summary": "Source - github", "url": "https://api.github.com/advisories/GHSA-ghc4-35x6-crw5" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd; osv", "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-ghc4-35x6-crw5" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/advisories/GHSA-ghc4-35x6-crw5" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/envoyproxy/envoy/commit/b6ba0b2294b98484fb0ed8556897d1073cc27867" }, { "category": "external", "summary": "Reference - github", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26308" }, { "category": "external", "summary": "Reference - certbundde", "url": "https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-0704.json" }, { "category": "external", "summary": "Reference - certbundde", "url": "https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-0704" }, { "category": "external", "summary": "Reference - certbundde", "url": "https://docs.cloud.google.com/support/bulletins#gcp-2026-013" }, { "category": "external", "summary": "Reference - certbundde", "url": "https://docs.cloud.google.com/service-mesh/docs/security-bulletins#gcp-2026-013" }, { "category": "external", "summary": "Reference - certbundde", "url": "https://access.redhat.com/errata/RHSA-2026:5952" }, { "category": "external", "summary": "Reference - certbundde", "url": "https://access.redhat.com/errata/RHSA-2026:5950" }, { "category": "external", "summary": "Reference - certbundde", "url": "https://access.redhat.com/errata/RHSA-2026:5948" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N", "baseScore": 7.5, "baseSeverity": "HIGH" }, "products": [ "CSAFPID-1317175", "CSAFPID-5777007", "CSAFPID-5777008", "CSAFPID-5777009", "CSAFPID-5777010", "CSAFPID-5780406", "CSAFPID-5780407", "CSAFPID-5780408", "CSAFPID-5780409", "CSAFPID-5795752", "CSAFPID-5810304", "CSAFPID-5810305", "CSAFPID-5810306", "CSAFPID-5810307", "CSAFPID-5810308" ] } ], "title": "CVE-2026-26308" } ] }