{"id":"CVE-2019-18835","aliases":["GHSA-cppw-2mf8-qpm5","PYSEC-2019-186"],"url":"https://o3.security/vulnerability/CVE-2019-18835","summary":"Improper Verification of Cryptographic Signature in matrix-synapse","details":"Matrix Synapse before 1.5.0 mishandles signature checking on some federation APIs. Events sent over /send_join, /send_leave, and /invite may not be correctly signed, or may not come from the expected servers.","published":"2019-11-08T00:15:10.413Z","modified":"2026-10-20T10:50:50.552676969Z","cvss":{"score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"epss":{"score":0.00864,"percentile":0.55469,"asOf":"2026-08-23"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"matrix-synapse","fixedVersion":"1.5.0"}],"fix":{"url":"https://github.com/matrix-org/synapse/pull/6262","label":"matrix-org/synapse#6262"},"references":[{"type":"ADVISORY","url":"https://github.com/matrix-org/synapse/releases/tag/v1.5.0"},{"type":"FIX","url":"https://github.com/matrix-org/synapse/pull/6262"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2019-18835"},{"type":"WEB","url":"https://github.com/matrix-org/synapse/commit/172f264ed38e8bef857552f93114b4ee113a880b"},{"type":"PACKAGE","url":"https://github.com/matrix-org/synapse"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2019-186.yaml"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-20T10:50:50.552676969Z"}}