{"id":"CVE-2023-45129","aliases":["ALPINE-CVE-2023-45129","DEBIAN-CVE-2023-45129","EUVD-2023-0135","GHSA-5chr-wjw5-3gq4","PYSEC-2023-199","UBUNTU-CVE-2023-45129","openSUSE-SU-2024:13320-1"],"status":"published","title":"matrix-synapse vulnerable to denial of service due to malicious server ACL events","description":"Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Prior to version 1.94.0, a malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service. Homeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected. Server administrators are advised to upgrade to Synapse 1.94.0 or later. As a workaround, rooms with malicious server ACL events can be purged and blocked using the admin API.","severity":{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.01394,"percentile":0.7257,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-770"],"published":"2023-10-10T17:17:11Z","modified":"2026-11-03T06:32:59Z","fixes":[{"ecosystem":"PyPI","package":"matrix-synapse","fixed_in":["1.94.0"],"sources":["ghsa","osv"]},{"ecosystem":"Alpine:v3.18","package":"synapse","fixed_in":["1.94.0-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.19","package":"synapse","fixed_in":["1.94.0-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.20","package":"synapse","fixed_in":["1.94.0-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.21","package":"synapse","fixed_in":["1.94.0-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.22","package":"synapse","fixed_in":["1.94.0-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.23","package":"synapse","fixed_in":["1.94.0-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.24","package":"synapse","fixed_in":["1.94.0-r0"],"sources":["osv"]},{"ecosystem":"openSUSE:Tumbleweed","package":"matrix-synapse","fixed_in":["1.94.0-2.1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"matrix-synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.94.0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.18","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.94.0-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.19","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.94.0-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.20","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.94.0-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.21","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.94.0-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.22","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.94.0-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.23","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.94.0-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.24","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.94.0-r0"}]}]},{"source":"osv","ecosystem":"PyPI","package":"matrix-synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.94.0"}]}],"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","1.11.0","1.11.0rc1","1.11.1","1.12.0","1.12.0rc1","1.12.1","1.12.1rc1","1.12.2","1.12.3","1.12.4","1.12.4rc1","1.13.0","1.13.0rc1","1.13.0rc2","1.13.0rc3","1.14.0","1.14.0rc1","1.14.0rc2","1.15.0","1.15.0rc1","1.15.1","1.15.2","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","1.47.0rc1","1.47.0rc2","1.47.0rc3","1.47.1","1.48.0","1.48.0rc1","1.49.0","1.49.0rc1","1.49.2","1.5.0","1.5.0rc1","1.5.0rc2","1.5.1","1.50.0","1.50.0rc1","1.50.0rc2","1.50.1","1.50.2","1.51.0","1.51.0rc1","1.51.0rc2","1.52.0","1.52.0rc1","1.53.0","1.53.0rc1","1.54.0","1.54.0rc1","1.55.0","1.55.0rc1","1.55.1","1.55.2","1.56.0","1.5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Advisory","advisory","web","report"]},{"url":"https://github.com/matrix-org/synapse/pull/16360","tags":["x_refsource_MISC","x_transferred","Patch","Vendor Advisory","fix","web","advisory","report"]},{"url":"https://matrix-org.github.io/synapse/latest/admin_api/rooms.html#version-2-new-version","tags":["x_refsource_MISC","x_transferred","Release Notes","web","report"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/WRO4MPQ6HOXIUZM6RJP6VTCTMV7RD2T3/","tags":["x_transferred","Mailing List","web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/KEVRB4MG5UXQ5RLZHSUJXM5GWEBYYS5B/","tags":["x_transferred","Mailing List","web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/N6P4QULVUE254WI7XF2LWWOGHCYVFXFY/","tags":["x_transferred","web"]},{"url":"https://security.gentoo.org/glsa/202401-12","tags":["x_transferred","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-45129","tags":["advisory"]},{"url":"https://github.com/matrix-org/synapse/commit/f84da3c32ec74cf054e2fd6d10618aa4997cffaa","tags":["web"]},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2023-199.yaml","tags":["web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/KEVRB4MG5UXQ5RLZHSUJXM5GWEBYYS5B","tags":["web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/N6P4QULVUE254WI7XF2LWWOGHCYVFXFY","tags":["web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/WRO4MPQ6HOXIUZM6RJP6VTCTMV7RD2T3","tags":["web"]},{"url":"https://github.com/advisories/GHSA-5chr-wjw5-3gq4"},{"url":"https://security.alpinelinux.org/vuln/CVE-2023-45129","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/45xxx/CVE-2023-45129.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2023-45129","tags":["advisory"]},{"url":"https://github.com/matrix-org/synapse","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2023-45129","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2023-45129","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2023-45129","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2023-45129","title":"matrix-synapse vulnerable to denial of service due to malicious server ACL events","description":"Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Prior to version 1.94.0, a malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service. Homeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected. Server administrators are advised to upgrade to Synapse 1.94.0 or later. As a workaround, rooms with malicious server ACL events can be purged and blocked using the admin API.","status":"published","published":"2023-10-10T17:17:11.146Z","modified":"2025-02-13T17:13:47.801Z","cvss":[{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:35:22.984825Z"}],"euvd":[{"id":"EUVD-2023-0135","description":"Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Prior to version 1.94.0, a malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service. Homeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected. Server administrators are advised to upgrade to Synapse 1.94.0 or later. As a workaround, rooms with malicious server ACL events can be purged and blocked using the admin API.","status":"published","published":"2023-10-10T17:17:11Z","modified":"2025-02-13T17:13:47Z","cvss":[{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-03T00:03:48.562419Z"}],"ghsa":[{"id":"GHSA-5chr-wjw5-3gq4","title":"matrix-synapse vulnerable to denial of service due to malicious server ACL events","description":"### Impact\nA malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service.\n\nHomeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected.\n\n### Patches\nServer administrators are advised to upgrade to Synapse 1.94.0 or later.\n\n### Workarounds\nRooms with malicious server ACL events can be [purged and blocked](https://matrix-org.github.io/synapse/latest/admin_api/rooms.html#version-2-new-version) using the admin API.\n","status":"published","published":"2023-10-10T21:27:53Z","modified":"2024-09-24T17:42:27Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"medium"},{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:38:05.526697Z"}],"nvd":[{"id":"CVE-2023-45129","description":"Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Prior to version 1.94.0, a malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service. Homeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected. Server administrators are advised to upgrade to Synapse 1.94.0 or later. As a workaround, rooms with malicious server ACL events can be purged and blocked using the admin API.","status":"published","published":"2023-10-10T18:15:19.093Z","modified":"2026-06-17T06:28:16.45Z","cvss":[{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"},{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"primary"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:08:36.656095Z"}],"osv":[{"id":"ALPINE-CVE-2023-45129","description":"Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Prior to version 1.94.0, a malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service. Homeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected. Server administrators are advised to upgrade to Synapse 1.94.0 or later. As a workaround, rooms with malicious server ACL events can be purged and blocked using the admin API.","status":"published","published":"2023-10-10T18:15:19.093Z","modified":"2026-11-03T06:32:59.385855886Z","cvss":[{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-03T07:16:09.603409Z"},{"id":"CVE-2023-45129","title":"matrix-synapse vulnerable to denial of service due to malicious server ACL events","description":"Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Prior to version 1.94.0, a malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service. Homeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected. Server administrators are advised to upgrade to Synapse 1.94.0 or later. As a workaround, rooms with malicious server ACL events can be purged and blocked using the admin API.","status":"published","published":"2023-10-10T17:17:11.146Z","modified":"2026-10-28T02:31:02.039361746Z","cvss":[{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:44:33.792101Z"},{"id":"DEBIAN-CVE-2023-45129","description":"Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Prior to version 1.94.0, a malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service. Homeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected. Server administrators are advised to upgrade to Synapse 1.94.0 or later. As a workaround, rooms with malicious server ACL events can be purged and blocked using the admin API.","status":"withdrawn","published":"2023-10-10T18:15:19.093Z","modified":"2026-08-11T20:49:51.597252437Z","cvss":[{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T15:45:40.275853Z"},{"id":"GHSA-5chr-wjw5-3gq4","title":"matrix-synapse vulnerable to denial of service due to malicious server ACL events","description":"### Impact\nA malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service.\n\nHomeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected.\n\n### Patches\nServer administrators are advised to upgrade to Synapse 1.94.0 or later.\n\n### Workarounds\nRooms with malicious server ACL events can be [purged and blocked](https://matrix-org.github.io/synapse/latest/admin_api/rooms.html#version-2-new-version) using the admin API.\n","status":"published","published":"2023-10-10T21:27:53Z","modified":"2026-09-10T03:49:58.536596047Z","cvss":[{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium"},{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:46:38.213481Z"},{"id":"PYSEC-2023-199","description":"Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Prior to version 1.94.0, a malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service. Homeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected. Server administrators are advised to upgrade to Synapse 1.94.0 or later. As a workaround, rooms with malicious server ACL events can be purged and blocked using the admin API.","status":"published","published":"2023-10-10T18:15:00Z","modified":"2023-11-08T04:13:36.77342Z","cvss":[{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T15:52:53.837392Z"},{"id":"UBUNTU-CVE-2023-45129","description":"Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Prior to version 1.94.0, a malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service. Homeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected. Server administrators are advised to upgrade to Synapse 1.94.0 or later. As a workaround, rooms with malicious server ACL events can be purged and blocked using the admin API.","status":"published","published":"2023-10-10T18:15:00Z","modified":"2025-09-08T16:56:32Z","cvss":[{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium"},{"version":"3.1","score":4.9,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T16:54:22.741943Z"},{"id":"openSUSE-SU-2024:13320-1","title":"matrix-synapse-1.94.0-2.1 on GA media","description":"These are all security issues fixed in the matrix-synapse-1.94.0-2.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2024-06-15T00:00:00Z","modified":"2026-02-04T02:32:55.030646Z","updated_at":"2026-11-02T16:58:36.025801Z"}]}}