{"id":"CVE-2026-45076","aliases":["ALPINE-CVE-2026-45076","DEBIAN-CVE-2026-45076","EUVD-2026-32934","GHSA-6qf2-7x63-mm6v","PYSEC-2026-194","UBUNTU-CVE-2026-45076","openSUSE-SU-2026:10898-1"],"status":"published","title":"Synapse pagination denial of service","description":"Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.","severity":{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00369,"percentile":0.31035,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-20"],"published":"2026-05-14T16:18:46Z","modified":"2026-11-06T00:30:03Z","fixes":[{"ecosystem":"PyPI","package":"matrix-synapse","fixed_in":["1.152.1"],"sources":["ghsa","osv"]},{"ecosystem":"Alpine:v3.23","package":"synapse","fixed_in":["1.152.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.24","package":"synapse","fixed_in":["1.152.1-r0"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"matrix-synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.152.1"}]}]},{"source":"osv","ecosystem":"Alpine:v3.23","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.152.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.24","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.152.1-r0"}]}]},{"source":"osv","ecosystem":"PyPI","package":"matrix-synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.152.1"}]}],"versions":["0.33.5","0.33.5.1","0.33.6","0.33.6rc1","0.33.7","0.33.7rc1","0.33.7rc2","0.33.8","0.33.8rc2","0.33.9","0.34.0","0.34.0.1","0.34.0rc1","0.34.0rc2","0.34.1.1","0.99.0","0.99.0rc1","0.99.0rc2","0.99.0rc3","0.99.0rc4","0.99.1","0.99.1.1","0.99.1rc1","0.99.1rc2","0.99.2","0.99.2rc1","0.99.3","0.99.3.1","0.99.3.2","0.99.3rc1","0.99.4","0.99.4rc1","0.99.5","0.99.5.1","0.99.5.2","0.99.5rc1","1.0.0","1.0.0rc1","1.0.0rc2","1.0.0rc3","1.1.0","1.1.0rc1","1.1.0rc2","1.10.0","1.10.0rc1","1.10.0rc2","1.10.0rc3","1.10.0rc5","1.10.1","1.100.0","1.100.0rc2","1.100.0rc3","1.101.0","1.101.0rc1","1.102.0","1.102.0rc1","1.103.0","1.103.0rc1","1.104.0","1.104.0rc1","1.105.0","1.105.0rc1","1.105.1","1.106.0","1.106.0rc1","1.107.0","1.107.0rc1","1.108.0","1.108.0rc1","1.109.0","1.109.0rc1","1.109.0rc2","1.109.0rc3","1.11.0","1.11.0rc1","1.11.1","1.110.0","1.110.0rc2","1.110.0rc3","1.111.0","1.111.0rc1","1.111.0rc2","1.111.1","1.112.0","1.112.0rc1","1.113.0","1.113.0rc1","1.114.0","1.114.0rc1","1.114.0rc3","1.115.0","1.115.0rc1","1.115.0rc2","1.116.0","1.116.0rc1","1.116.0rc2","1.117.0","1.117.0rc1","1.118.0","1.118.0rc1","1.119.0","1.119.0rc2","1.12.0","1.12.0rc1","1.12.1","1.12.1rc1","1.12.2","1.12.3","1.12.4","1.12.4rc1","1.120.0","1.120.0rc1","1.120.2","1.121.0","1.121.0rc1","1.121.1","1.122.0","1.122.0rc1","1.123.0","1.123.0rc1","1.124.0","1.124.0rc1","1.124.0rc2","1.124.0rc3","1.125.0","1.125.0rc1","1.126.0","1.126.0rc2","1.126.0rc3","1.127.0","1.127.0rc1","1.127.1","1.128.0","1.128.0rc1","1.129.0","1.129.0rc2","1.13.0","1.13.0rc1","1.13.0rc2","1.13.0rc3","1.130.0","1.130.0rc1","1.131.0","1.131.0rc1","1.132.0","1.132.0rc1","1.133.0","1.133.0rc1","1.134.0","1.134.0rc1","1.135.0","1.135.0rc1","1.135.0rc2","1.135.2","1.136.0","1.136.0rc1","1.136.0rc2","1.137.0","1.137.0rc1","1.138.0","1.138.0rc1","1.138.2","1.138.3","1.138.4","1.139.0","1.139.0rc2","1.139.0rc3","1.139.1","1.139.2","1.14.0","1.14.0rc1","1.14.0rc2","1.140.0","1.140.0rc1","1.141.0","1.141.0rc1","1.141.0rc2","1.142.0","1.142.0rc3","1.142.0rc4","1.142.1","1.143.0","1.143.0rc2","1.144.0","1.144.0rc1","1.145.0","1.145.0rc1","1.145.0rc2","1.145.0rc3","1.145.0rc4","1.146.0","1.146.0rc1","1.147.0","1.147.0rc1","1.147.1","1.148.0","1.148.0rc1","1.149.0","1.149.0rc1","1.149.1","1.15.0","1.15.0rc1","1.15.1","1.15.2","1.150.0","1.150.0rc1","1.151.0","1.151.0rc1","1.152.0","1.152.0rc1","1.16.0","1.16.0rc1","1.16.0rc2","1.16.1","1.17.0","1.17.0rc1","1.18.0","1.18.0rc1","1.18.0rc2","1.19.0","1.19.0rc1","1.19.1","1.19.1rc1","1.19.2","1.19.3","1.2.0","1.2.0rc1","1.2.0rc2","1.2.1","1.20.0","1.20.0rc1","1.20.0rc2","1.20.0rc3","1.20.0rc4","1.20.0rc5","1.20.1","1.21.0","1.21.0rc1","1.21.0rc2","1.21.0rc3","1.21.1","1.21.2","1.22.0","1.22.0rc1","1.22.0rc2","1.22.1","1.23.0","1.23.0rc1","1.23.1","1.24.0","1.24.0rc1","1.24.0rc2","1.25.0","1.25.0rc1","1.26.0","1.26.0rc1","1.26.0rc2","1.27.0","1.27.0rc1","1.27.0rc2","1.28.0","1.28.0rc1","1.29.0","1.29.0rc1","1.3.0","1.3.0rc1","1.3.1","1.30.0","1.30.0rc1","1.30.1","1.31.0","1.31.0rc1","1.32.0","1.32.0rc1","1.32.1","1.32.2","1.33.0","1.33.0rc1","1.33.0rc2","1.33.1","1.33.2","1.34.0","1.34.0rc1","1.35.0","1.35.0rc1","1.35.0rc2","1.35.0rc3","1.35.1","1.36.0","1.36.0rc1","1.36.0rc2","1.37.0","1.37.0rc1","1.37.1","1.37.1rc1","1.38.0","1.38.0rc1","1.38.0rc2","1.38.0rc3","1.38.1","1.39.0","1.39.0rc1","1.39.0rc2","1.39.0rc3","1.4.0","1.4.0rc1","1.4.0rc2","1.4.1","1.4.1rc1","1.40.0","1.40.0rc1","1.40.0rc2","1.40.0rc3","1.41.0","1.41.0rc1","1.41.1","1.42.0","1.42.0rc1","1.42.0rc2","1.43.0","1.43.0rc1","1.43.0rc2","1.44.0","1.44.0rc1","1.44.0rc2","1.44.0rc3","1.45.0","1.45.0rc1","1.45.0rc2","1.45.1","1.46.0","1.46.0rc1","1.47.0","1.4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Advisory","advisory","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45076","tags":["advisory"]},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2026-194.yaml","tags":["web"]},{"url":"https://github.com/advisories/GHSA-6qf2-7x63-mm6v"},{"url":"https://security.alpinelinux.org/vuln/CVE-2026-45076","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45076.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-45076","tags":["advisory"]},{"url":"https://github.com/element-hq/synapse","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-45076","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-45076","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2026-45076","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-45078","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2026-45076","title":"Synapse pagination denial of service","description":"Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.","status":"published","published":"2026-05-28T15:50:25.842Z","modified":"2026-06-02T14:51:34.553Z","cvss":[{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium","assessor":"cna"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T13:46:43.922571Z"}],"euvd":[{"id":"EUVD-2026-32934","description":"Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.","status":"published","published":"2026-05-28T15:50:25Z","modified":"2026-06-02T14:51:34Z","cvss":[{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"updated_at":"2026-11-02T18:20:56.053165Z"}],"ghsa":[{"id":"GHSA-6qf2-7x63-mm6v","title":"Synapse pagination Denial of Service","description":"### 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).","status":"published","published":"2026-05-14T16:18:46Z","modified":"2026-06-09T10:18:37Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T14:40:22.540562Z"}],"nvd":[{"id":"CVE-2026-45076","description":"Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.","status":"published","published":"2026-05-28T17:16:31.59Z","modified":"2026-10-26T13:10:00.14Z","cvss":[{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"},{"version":"3.1","score":2.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","level":"low","assessor":"primary"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T14:12:21.244426Z"}],"osv":[{"id":"ALPINE-CVE-2026-45076","description":"Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.","status":"published","published":"2026-05-28T17:16:31.59Z","modified":"2026-11-06T00:30:03.048565501Z","cvss":[{"version":"3.1","score":2.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","level":"low"}],"updated_at":"2026-11-06T01:02:32.613973Z"},{"id":"CVE-2026-45076","title":"Synapse pagination denial of service","description":"Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.","status":"published","published":"2026-05-28T15:50:25.842Z","modified":"2026-10-28T02:30:32.44146336Z","cvss":[{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T15:45:05.172514Z"},{"id":"DEBIAN-CVE-2026-45076","description":"Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.","status":"withdrawn","published":"2026-05-28T17:16:31.59Z","modified":"2026-08-11T20:49:53.664375163Z","cvss":[{"version":"3.1","score":2.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","level":"low"}],"updated_at":"2026-11-02T15:45:55.669088Z"},{"id":"GHSA-6qf2-7x63-mm6v","title":"Synapse pagination Denial of Service","description":"### 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).","status":"published","published":"2026-05-14T16:18:46Z","modified":"2026-09-10T03:50:45.939755552Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T15:46:39.965326Z"},{"id":"PYSEC-2026-194","description":"Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.","status":"published","published":"2026-05-28T17:16:31.59Z","modified":"2026-06-05T12:45:16.338802941Z","cvss":[{"version":"3.1","score":2.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","level":"low"}],"updated_at":"2026-11-02T15:52:55.537808Z"},{"id":"UBUNTU-CVE-2026-45076","description":"Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.","status":"published","published":"2026-05-28T17:16:00Z","modified":"2026-06-08T09:45:10.761696117Z","cvss":[{"version":"4.0","score":5.1,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"},{"version":"3.1","score":2.7,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","level":"low"}],"updated_at":"2026-11-02T16:56:26.396868Z"},{"id":"openSUSE-SU-2026:10898-1","title":"matrix-synapse-1.153.0-2.1 on GA media","description":"These are all security issues fixed in the matrix-synapse-1.153.0-2.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-05-29T00:00:00Z","modified":"2026-05-30T23:15:07.914094071Z","updated_at":"2026-11-02T16:58:38.95195Z"}]}}