{"id":"GHSA-w9mh-5x8j-9754","summary":"Malicious Matrix homeserver can leak truncated message content of messages it shouldn't have access to","details":"### Impact\n\nThe fix for GHSA-wm4w-7h2q-3pf7 / [CVE-2024-32000](https://www.cve.org/CVERecord?id=CVE-2024-32000) included in matrix-appservice-irc 2.0.0 relied on the Matrix homeserver-provided timestamp to determine whether a user has access to the event they're replying to when determining whether or not to include a truncated version of the original event in the IRC message. Since this value is controlled by external entities, a malicious Matrix homeserver joined to a room in which a matrix-appservice-irc bridge instance (before version 2.0.1) is present can fabricate the timestamp with the intent of tricking the bridge into leaking room messages the homeserver should not have access to.\n\n### Patches\n\nmatrix-appservice-irc 2.0.1 [drops the reliance](https://github.com/matrix-org/matrix-appservice-irc/pull/1804) on `origin_server_ts` when determining whether or not an event should be visible to a user, instead tracking the event timestamps internally.\n\n### Workarounds\n\nIt's possible to limit the amount of information leaked by setting a reply template that doesn't contain the original message. See [these lines](https://github.com/matrix-org/matrix-appservice-irc/blob/d5d67d1d3ea3f0f6962a0af2cc57b56af3ad2129/config.sample.yaml#L601-L604) in the configuration file.\n\n### References\n\n- Patch: https://github.com/matrix-org/matrix-appservice-irc/pull/1804\n\n### For more information\n\nIf you have any questions or comments about this advisory, please email us at [security at matrix.org](mailto:security@matrix.org).","aliases":["CVE-2024-39691"],"modified":"2026-09-10T03:50:16.894989056Z","published":"2024-07-05T20:06:06Z","database_specific":{"cwe_ids":["CWE-280","CWE-755"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2024-07-05T20:06:06Z","nvd_published_at":"2024-07-05T19:15:10Z"},"references":[{"type":"WEB","url":"https://github.com/matrix-org/matrix-appservice-irc/security/advisories/GHSA-w9mh-5x8j-9754"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-39691"},{"type":"WEB","url":"https://github.com/matrix-org/matrix-appservice-irc/pull/1804"},{"type":"WEB","url":"https://github.com/matrix-org/matrix-appservice-irc/commit/1835e047f269001054be4c68867797aa12372a0f"},{"type":"PACKAGE","url":"https://github.com/matrix-org/matrix-appservice-irc"},{"type":"WEB","url":"https://github.com/matrix-org/matrix-appservice-irc/blob/d5d67d1d3ea3f0f6962a0af2cc57b56af3ad2129/config.sample.yaml#L601-L604"}],"affected":[{"package":{"name":"matrix-appservice-irc","ecosystem":"npm","purl":"pkg:npm/matrix-appservice-irc"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.0.1"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 2.0.0","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/07/GHSA-w9mh-5x8j-9754/GHSA-w9mh-5x8j-9754.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"}]}