{"id":"CVE-2024-31208","aliases":["GHSA-3h7q-rfh9-xm4v","PYSEC-2024-50"],"title":"Synapse V2 state resolution weakness allows Denial of Service (DoS)","summary":"Synapse V2 state resolution weakness allows Denial of Service (DoS)","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","vendor":"matrix-synapse","product":"matrix-synapse","ecosystem":"pip","affected":["matrix-synapse < 1.105.1"],"patched":["matrix-synapse 1.105.1"],"published":"2024-04-23","updated":"2026-09-10","sourceUpdated":"2026-09-10T03:50:11.151283540Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-3h7q-rfh9-xm4v","references":[{"url":"https://github.com/element-hq/synapse/security/advisories/GHSA-3h7q-rfh9-xm4v"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2024-31208"},{"url":"https://github.com/element-hq/synapse/commit/55b0aa847a61774b6a3acdc4b177a20dc019f01a"},{"url":"https://github.com/element-hq/synapse"},{"url":"https://github.com/element-hq/synapse/releases/tag/v1.105.1"},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2024-50.yaml"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/R6FCCO4ODTZ3FDS7TMW76PKOSEL2TQVB"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/RR53FNHV446CB37TP45GZ6F6HZLZCK3K"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VSF4NJJSTSQRJQ47PLYYSCFYKJBP7DET"}],"tags":["osv","pip"],"epss":0.01463,"epssPercentile":0.72476,"ingestedAt":"2026-09-12T03:13:01.646Z","slug":"CVE-2024-31208","body":"## Overview\n\n### Impact\n\nA remote Matrix user with malicious intent, sharing a room with Synapse instances before 1.105.1, can dispatch specially crafted events to exploit a weakness in how the auth chain cover index is calculated. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service.\n\nServers in private federations, or those that do not federate, are not affected.\n\n### Patches\n\nServer administrators should upgrade to 1.105.1 or later.\n\n### Workarounds\n\nOne can:\n- ban the malicious users or ACL block servers from the rooms; and/or\n- leave the room and purge the room using the admin API\n\n### For more information\n\nIf you have any questions or comments about this advisory, please email us at [security AT element.io](mailto:security@element.io).\n\n## Affected packages\n\n- `matrix-synapse < 1.105.1`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `matrix-synapse 1.105.1`","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0.3,"exploitation":0,"ransomware":0},"changes":[]}