{ "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-2026-5199", "tracking": { "current_release_date": "2026-04-02T14:57:06.665105Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-5199", "initial_release_date": "2026-04-01T18:40:46.845015Z", "revision_history": [ { "date": "2026-04-01T18:40:46.845015Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (2).| References created (2).| CWES updated (1).| Unknown change." }, { "date": "2026-04-01T18:40:54.320272Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-04-01T23:05:50.048520Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-04-01T23:05:56.091981Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-04-02T14:54:34.896034Z", "number": "5", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-04-02T14:54:40.544461Z", "number": "6", "summary": "NCSC Score updated." } ], "status": "interim", "version": "6" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:semver/1.29.0|<1.29.5", "product": { "name": "vers:semver/1.29.0|<1.29.5", "product_id": "CSAFPID-5982385" } }, { "category": "product_version_range", "name": "vers:semver/1.30.0|<1.30.3", "product": { "name": "vers:semver/1.30.0|<1.30.3", "product_id": "CSAFPID-5982386" } } ], "category": "product_name", "name": "temporal" } ], "category": "vendor", "name": "Temporal Technologies, Inc." } ] }, "vulnerabilities": [ { "cve": "CVE-2026-5199", "cwe": { "id": "CWE-639", "name": "Authorization Bypass Through User-Controlled Key" }, "notes": [ { "category": "description", "text": "A writer role user in an attacker-controlled namespace could signal, delete, and reset workflows or activities in a victim namespace on the same cluster. Exploitation requires the attacker to know or guess specific victim workflow ID(s) and, for signal operations, signal names. This was due to a bug introduced in Temporal Server v1.29.0 which inadvertently allowed an attacker to control the namespace name value instead of using the server's own trusted name value within the batch activity code. The batch activity validated the namespace ID but did not cross-check the namespace name against the worker's bound namespace, allowing the per-namespace worker's privileged credentials to operate on an arbitrary namespace. Exploitation requires a server configuration where internal components have cross-namespace authorization, such as deployment of the internal-frontend service or equivalent TLS-based authorization for internal identities.\n\n\n\n\nThis vulnerability also impacted Temporal Cloud when the attacker and victim namespaces were on the same cell, with the same preconditions as self-hosted clusters.", "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/5xxx/CVE-2026-5199.json" }, { "category": "description", "text": "A writer role user in an attacker-controlled namespace could signal, delete, and reset workflows or activities in a victim namespace on the same cluster. Exploitation requires the attacker to know or guess specific victim workflow ID(s) and, for signal operations, signal names. This was due to a bug introduced in Temporal Server v1.29.0 which inadvertently allowed an attacker to control the namespace name value instead of using the server's own trusted name value within the batch activity code. The batch activity validated the namespace ID but did not cross-check the namespace name against the worker's bound namespace, allowing the per-namespace worker's privileged credentials to operate on an arbitrary namespace. Exploitation requires a server configuration where internal components have cross-namespace authorization, such as deployment of the internal-frontend service or equivalent TLS-based authorization for internal identities.\n\n\n\n\nThis vulnerability also impacted Temporal Cloud when the attacker and victim namespaces were on the same cell, with the same preconditions as self-hosted clusters.", "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-5199" }, { "category": "other", "text": "0.00038", "title": "EPSS" }, { "category": "other", "text": "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:L/SA:L/S:N/AU:Y/R:U/RE:M", "title": "CVSSV4" }, { "category": "other", "text": "2.3", "title": "CVSSV4 base score" }, { "category": "other", "text": "3.9", "title": "NCSC Score" }, { "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 CVSS (V3) score", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5982385", "CSAFPID-5982386" ] }, "references": [ { "category": "external", "summary": "Source - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/5xxx/CVE-2026-5199.json" }, { "category": "external", "summary": "Source - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-5199" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Reference - cveprojectv5; nvd", "url": "https://github.com/temporalio/temporal/releases/tag/v1.29.5" }, { "category": "external", "summary": "Reference - cveprojectv5; nvd", "url": "https://github.com/temporalio/temporal/releases/tag/v1.30.3" } ], "title": "CVE-2026-5199" } ] }