{"api_version":"1","generated_at":"2026-04-23T05:15:39+00:00","cve":"CVE-2023-38691","urls":{"html":"https://cve.report/CVE-2023-38691","api":"https://cve.report/api/cve/CVE-2023-38691.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2023-38691","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2023-38691"},"summary":{"title":"CVE-2023-38691","description":"matrix-appservice-bridge provides an API for setting up bridges. Starting in version 4.0.0 and prior to versions 8.1.2 and 9.0.1, a malicious Matrix server can use a foreign user's MXID in an OpenID exchange, allowing a bad actor to impersonate users when using the provisioning API. The library does not check that the servername part of the `sub` parameter (containing the user's *claimed* MXID) is the the same as the servername we are talking to. A malicious actor could spin up a server on any given domain, respond with a `sub` parameter according to the user they want to act as and use the resulting token to perform provisioning requests. Versions 8.1.2 and 9.0.1 contain a patch. As a workaround, disable the provisioning API.","state":"PUBLIC","assigner":"security-advisories@github.com","published_at":"2023-08-04 17:15:00","updated_at":"2023-08-11 19:34:00"},"problem_types":["CWE-287"],"metrics":[],"references":[{"url":"https://github.com/matrix-org/matrix-appservice-bridge/security/advisories/GHSA-vc7j-h8xg-fv5x","name":"https://github.com/matrix-org/matrix-appservice-bridge/security/advisories/GHSA-vc7j-h8xg-fv5x","refsource":"MISC","tags":[],"title":"matrix-appservice-bridge doesn't verify the sub parameter of an openId token exchange, allowing unauthorized access to provisioning APIs · Advisory · matrix-org/matrix-appservice-bridge · GitHub","mime":"text/html","httpstatus":"200","archivestatus":"404"},{"url":"https://github.com/matrix-org/matrix-appservice-bridge/commit/4c6723a5e7beda65cdf1ae5dbb882e8beaac8552","name":"https://github.com/matrix-org/matrix-appservice-bridge/commit/4c6723a5e7beda65cdf1ae5dbb882e8beaac8552","refsource":"MISC","tags":[],"title":"Merge pull request from GHSA-vc7j-h8xg-fv5x · matrix-org/matrix-appservice-bridge@4c6723a · GitHub","mime":"text/html","httpstatus":"200","archivestatus":"404"},{"url":"https://www.cve.org/CVERecord?id=CVE-2023-38691","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-38691","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[{"cve_year":"2023","cve_id":"38691","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"a","cpe4":"matrix","cpe5":"matrix-appservice-bridge","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"node.js","cpe12":"*","cpe13":"*"},{"cve_year":"2023","cve_id":"38691","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"a","cpe4":"matrix","cpe5":"matrix-appservice-bridge","cpe6":"9.0.0","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"node.js","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"data_version":"4.0","data_type":"CVE","data_format":"MITRE","CVE_data_meta":{"ID":"CVE-2023-38691","ASSIGNER":"security-advisories@github.com","STATE":"PUBLIC"},"description":{"description_data":[{"lang":"eng","value":"matrix-appservice-bridge provides an API for setting up bridges. 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