{"id":"CVE-2018-16515","aliases":["GHSA-fmvh-rvq5-hhjx","PYSEC-2026-845"],"url":"https://o3.security/vulnerability/CVE-2018-16515","summary":"Matrix Synapse Improper Signature Validation","details":"Matrix Synapse before 0.33.3.1 allows remote attackers to spoof events and possibly have unspecified other impacts by leveraging improper transaction and event signature validation.","published":"2018-09-18T21:29:03.010Z","modified":"2026-07-08T05:52:20.525647792Z","cvss":{"score":8.8,"severity":"HIGH","vector":"CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"matrix-synapse","fixedVersion":"0.33.3.1"},{"ecosystem":"PyPI","name":"matrix-synapse","fixedVersion":"0.33.2.1"}],"fix":null,"references":[{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IRW7YR2H3ASUSYX4AO4KMY3FNVDNYW3P/"},{"type":"ADVISORY","url":"https://matrix.org/blog/2018/09/06/critical-security-update-synapse-0-33-3-1/"},{"type":"FIX","url":"https://github.com/matrix-org/synapse/issues/3796#event-1833126269"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-08T05:52:20.525647792Z"}}