{"id":"CVE-2018-12291","aliases":["GHSA-v8wm-g9f2-xjv4","PYSEC-2026-664"],"title":"Matrix Synapse Security Filtering Flaw","summary":"Matrix Synapse Security Filtering Flaw","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","vendor":"matrix-synapse","product":"matrix-synapse","ecosystem":"pip","affected":["matrix-synapse < 0.31.1"],"patched":["matrix-synapse 0.31.1"],"published":"2022-05-13","updated":"2026-07-06","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-v8wm-g9f2-xjv4","references":[{"url":"https://nvd.nist.gov/vuln/detail/CVE-2018-12291"},{"url":"https://github.com/matrix-org/synapse/pull/3371"},{"url":"https://github.com/matrix-org/synapse/commit/0834b49c6a9b6c597a154d4b2dfcf8fff90699ec"},{"url":"https://github.com/matrix-org/synapse"},{"url":"https://github.com/matrix-org/synapse/releases/tag/v0.31.1"}],"tags":["osv","pip"],"epss":0.01647,"epssPercentile":0.75029,"ingestedAt":"2026-07-08T18:25:53.278Z","slug":"CVE-2018-12291","body":"## Overview\n\nThe `on_get_missing_events` function in handlers/federation.py in Matrix Synapse before 0.31.1 has a security bug in the get_missing_events federation API where event visibility rules were not applied correctly.\n\n## Affected packages\n\n- `matrix-synapse < 0.31.1`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `matrix-synapse 0.31.1`","depth":"twilight","depthScore":42,"depthScoreParts":{"impact":41.3,"likelihood":0.3,"exploitation":0,"ransomware":0},"changes":[]}