{"id":"CVE-2026-45076","aliases":["GHSA-6qf2-7x63-mm6v","PYSEC-2026-194"],"title":"Synapse pagination Denial of Service","summary":"Synapse pagination Denial of Service","severity":"medium","vendor":"matrix-synapse","product":"matrix-synapse","ecosystem":"pip","affected":["matrix-synapse < 1.152.1"],"patched":["matrix-synapse 1.152.1"],"published":"2026-05-14","updated":"2026-09-10","sourceUpdated":"2026-09-10T03:50:45.939755552Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-6qf2-7x63-mm6v","references":[{"url":"https://github.com/element-hq/synapse/security/advisories/GHSA-6qf2-7x63-mm6v"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45076"},{"url":"https://github.com/element-hq/synapse"},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2026-194.yaml"}],"tags":["osv","pip"],"epss":0.00369,"epssPercentile":0.30734,"ingestedAt":"2026-09-12T03:13:01.667Z","slug":"CVE-2026-45076","body":"## Overview\n\n### Impact\n\nIn federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients.\n\nClients could therefore fail to display room history.\n\n### Patches\n\nUpdate to Synapse 1.152.1 or later.\n\n### Workarounds\n\nThere are no known workarounds for this issue.\n\n### Identifiers\n\n- ELEMENTSEC-2025-1636\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 < 1.152.1`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `matrix-synapse 1.152.1`","depth":"sunlit","depthScore":28,"depthScoreParts":{"impact":27.5,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}