{"id":"CVE-2022-39249","aliases":["GHSA-6263-x97c-c4gg"],"url":"https://o3.security/vulnerability/CVE-2022-39249","summary":"Matrix Javascript SDK vulnerable to impersonation via forwarded Megolm sessions","details":"Matrix Javascript SDK is the Matrix Client-Server SDK for JavaScript. Prior to version 19.7.0, an attacker cooperating with a malicious homeserver can construct messages appearing to have come from another person. Such messages will be marked with a grey shield on some platforms, but this may be missing in others. This attack is possible due to the matrix-js-sdk implementing a too permissive key forwarding strategy on the receiving end. Starting with version 19.7.0, the default policy for accepting key forwards has been made more strict in the matrix-js-sdk. matrix-js-sdk will now only accept forwarded keys in response to previously issued requests and only from own, verified devices. The SDK now sets a `trusted` flag on the decrypted message upon decryption, based on whether the key used to decrypt the message was received from a trusted source. Clients need to ensure that messages decrypted with a key with `trusted = false` are decorated appropriately, for example, by showing a warning for such messages. This attack requires coordination between a malicious homeserver and an attacker, and those who trust your homeservers do not need a workaround.","published":"2022-09-28T00:00:00Z","modified":"2026-07-15T01:49:00.491150879Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"matrix-js-sdk","fixedVersion":"19.7.0"}],"fix":{"url":"https://github.com/matrix-org/matrix-js-sdk/commit/a587d7c36026fe1fcf93dfff63588abee359be76","label":"matrix-org/matrix-js-sdk@a587d7c"},"references":[{"type":"WEB","url":"https://github.com/matrix-org/matrix-js-sdk/releases/tag/v19.7.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/39xxx/CVE-2022-39249.json"},{"type":"ADVISORY","url":"https://github.com/matrix-org/matrix-js-sdk/security/advisories/GHSA-6263-x97c-c4gg"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2022-39249"},{"type":"ADVISORY","url":"https://security.gentoo.org/glsa/202210-35"},{"type":"FIX","url":"https://github.com/matrix-org/matrix-js-sdk/commit/a587d7c36026fe1fcf93dfff63588abee359be76"},{"type":"FIX","url":"https://github.com/matrix-org/matrix-spec-proposals/pull/3061"},{"type":"ARTICLE","url":"https://matrix.org/blog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-matrix-sdks-and-clients"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-15T01:49:00.491150879Z"}}