{"id":"CVE-2022-39257","state":"PUBLISHED","title":"Matrix iOS SDK vulnerable to impersonation via forwarded Megolm sessions","description":"Matrix iOS SDK allows developers to build iOS apps compatible with Matrix. Prior to version 0.23.19, 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-ios-sdk implementing a too permissive key forwarding strategy. The default policy for accepting key forwards has been made more strict in the matrix-ios-sdk version 0.23.19. matrix-ios-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 home server and an attacker, so those who trust their home servers do not need a workaround.","publishedAt":"2022-09-28T20:55:10.000Z","updatedAt":"2025-04-23T16:54:28.718Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["matrix-org matrix-ios-sdk"],"affected":[{"vendor":"matrix-org","product":"matrix-ios-sdk","versions":[{"version":"< 0.23.19","status":"affected"}]}],"references":["https://matrix.org/blog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-matrix-sdks-and-clients","https://github.com/matrix-org/matrix-ios-sdk/commit/5ca86c328a5faaab429c240551cb9ca8f0f6262c","https://github.com/matrix-org/matrix-ios-sdk/releases/tag/v0.23.19","https://github.com/matrix-org/matrix-ios-sdk/security/advisories/GHSA-qxr3-5jmq-xcf4"],"weaknesses":["CWE-322","CWE-287"],"ingestedAt":"2026-10-29T19:50:29.496Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2022/39xxx/CVE-2022-39257.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.1","cveMetadata":{"cveId":"CVE-2022-39257","state":"PUBLISHED","datePublished":"2022-09-28T20:55:10.000Z","dateUpdated":"2025-04-23T16:54:28.718Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2022-09-02T00:00:00.000Z"},"containers":{"cna":{"title":"Matrix iOS SDK vulnerable to impersonation via forwarded Megolm sessions","descriptions":[{"lang":"en","value":"Matrix iOS SDK allows developers to build iOS apps compatible with Matrix. 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