{"id":"CVE-2024-31208","aliases":["DEBIAN-CVE-2024-31208","EUVD-2024-0099","GHSA-3h7q-rfh9-xm4v","PYSEC-2024-50","UBUNTU-CVE-2024-31208","USN-7444-1","openSUSE-SU-2024:13897-1"],"status":"published","title":"Synapse's V2 state resolution weakness allows DoS from remote room members","description":"Synapse is an open-source Matrix homeserver. A 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 the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.01463,"percentile":0.73844,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-770"],"published":"2024-04-23T17:26:39Z","modified":"2026-10-28T02:30:27Z","fixes":[{"ecosystem":"PyPI","package":"matrix-synapse","fixed_in":["1.105.1"],"sources":["ghsa","osv"]},{"ecosystem":"Ubuntu:Pro:22.04:LTS","package":"matrix-synapse","fixed_in":["1.53.0-1ubuntu0.1~esm2"],"sources":["osv"]},{"ecosystem":"openSUSE:Tumbleweed","package":"matrix-synapse","fixed_in":["1.105.1-1.1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"matrix-synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.105.1"}]}]},{"source":"osv","ecosystem":"PyPI","package":"matrix-synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.105.1"}]}],"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","1.11.0","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","1.56.0rc1","1.57.0","1.57.0rc1","1.57.1","1.58.0","1.58.0rc2","1.58.1","1.59.0","1.59.0rc1","1.59.0rc2","1.59.1","1.6.0","1.6.0rc1","1.6.0rc2","1.6.1","1.60.0","1.60.0rc1","1.60.0rc2","1.61.0","1.61.0rc1","1.61.1","1.62.0","1.62.0rc1","1.62.0rc2","1.62.0rc3","1.63.0","1.63.0rc1","1.63.1","1.64.0","1.64.0rc1","1.64.0rc2","1.65.0","1.65.0rc1","1.65.0rc2","1.66.0","1.66.0rc1","1.66.0rc2","1.67.0","1.67.0rc1","1.68.0","1.68.0rc1","1.68.0rc2","1.69.0","1.69.0rc1","1.69.0rc2","1.69.0rc4","1.7.0","1.7.0rc1","1.7.0rc2","1.7.1","1.7.2","1.7.3","1.70.0","1.70.0rc1","1.70.0rc2","1.70.1","1.71.0","1.71.0rc1","1.71.0rc2","1.72.0","1.72.0rc1","1.73.0","1.73.0rc2","1.74.0","1.74.0rc1","1.75.0","1.75.0rc1","1.75.0rc2","1.76.0","1.76.0rc1","1.76.0rc2","1.77.0","1.77.0rc1","1.77.0rc2","1.78.0","1.78.0rc1","1.79.0","1.79.0rc1","1.79.0rc2","1.8.0","1.8.0rc1","1.80.0","1.80.0rc1","1.80.0rc2","1.81.0","1.81.0rc1","1.81.0rc2","1.82.0","1.82.0rc1","1.83.0","1.83.0rc1","1.84.0","1.84.0rc1","1.84.1","1.85.0","1.85.0rc1","1.85.0rc2","1.85.1","1.85.2","1.86.0","1.86.0rc2","1.87.0","1.87.0rc1","1.88.0","1.88.0rc1","1.89.0","1.89.0rc1","1.9.0","1.9.0.dev1","1.9.0.dev2","1.9.0rc1","1.9.1","1.90.0","1.90.0rc1","1.91.0","1.91.0rc1","1.91.1","1.91.2","1.92.0rc1","1.92.1","1.92.2","1.92.3","1.93.0","1.93.0rc1","1.94.0","1.94.0rc1","1.95.0","1.95.0rc1","1.95.1","1.96.0rc1","1.96.1","1.97.0","1.97.0rc1","1.98.0","1.98.0r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Advisory","advisory","web","report"]},{"url":"https://github.com/element-hq/synapse/commit/55b0aa847a61774b6a3acdc4b177a20dc019f01a","tags":["x_refsource_MISC","x_transferred","Patch","fix","web","report"]},{"url":"https://github.com/element-hq/synapse/releases/tag/v1.105.1","tags":["x_refsource_MISC","x_transferred","Release Notes","web","report"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/RR53FNHV446CB37TP45GZ6F6HZLZCK3K/","tags":["x_transferred","Mailing List","Third Party Advisory","web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/R6FCCO4ODTZ3FDS7TMW76PKOSEL2TQVB/","tags":["x_transferred","Mailing List","Third Party Advisory","web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VSF4NJJSTSQRJQ47PLYYSCFYKJBP7DET/","tags":["x_transferred","Mailing List","Third Party Advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2024-31208","tags":["advisory"]},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2024-50.yaml","tags":["web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/R6FCCO4ODTZ3FDS7TMW76PKOSEL2TQVB","tags":["web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/RR53FNHV446CB37TP45GZ6F6HZLZCK3K","tags":["web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VSF4NJJSTSQRJQ47PLYYSCFYKJBP7DET","tags":["web"]},{"url":"https://github.com/advisories/GHSA-3h7q-rfh9-xm4v"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/31xxx/CVE-2024-31208.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2024-31208","tags":["advisory"]},{"url":"https://github.com/element-hq/synapse","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2024-31208","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2024-31208","tags":["report"]},{"url":"https://ubuntu.com/security/notices/USN-7444-1","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2022-39335","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2022-39374","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2023-32683","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2023-41335","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2023-42453","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2023-43796","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2024-53863","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2024-31208","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2024-31208","title":"Synapse's V2 state resolution weakness allows DoS from remote room members","description":"Synapse is an open-source Matrix homeserver. A 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 the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.","status":"published","published":"2024-04-23T17:26:39.171Z","modified":"2025-02-13T17:47:51.943Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:34:14.308905Z"}],"euvd":[{"id":"EUVD-2024-0099","description":"Synapse is an open-source Matrix homeserver. A 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 the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.","status":"published","published":"2024-04-23T17:26:39Z","modified":"2025-02-13T17:47:51Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T20:53:31.829035Z"}],"ghsa":[{"id":"GHSA-3h7q-rfh9-xm4v","title":"Synapse V2 state resolution weakness allows Denial of Service (DoS)","description":"### 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).","status":"published","published":"2024-04-23T21:15:46Z","modified":"2024-05-04T17:29:46Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:37:48.08826Z"}],"nvd":[{"id":"CVE-2024-31208","description":"Synapse is an open-source Matrix homeserver. A 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 the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.","status":"published","published":"2024-04-23T18:15:14.457Z","modified":"2026-06-17T07:27:59.037Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:09:53.50104Z"}],"osv":[{"id":"CVE-2024-31208","title":"Synapse's V2 state resolution weakness allows DoS from remote room members","description":"Synapse is an open-source Matrix homeserver. A 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 the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.","status":"published","published":"2024-04-23T17:26:39.171Z","modified":"2026-10-28T02:30:27.974583541Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:44:40.06138Z"},{"id":"DEBIAN-CVE-2024-31208","description":"Synapse is an open-source Matrix homeserver. A 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 the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.","status":"withdrawn","published":"2024-04-23T18:15:14.457Z","modified":"2026-08-11T20:49:51.580797762Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T15:45:42.530184Z"},{"id":"GHSA-3h7q-rfh9-xm4v","title":"Synapse V2 state resolution weakness allows Denial of Service (DoS)","description":"### 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).","status":"published","published":"2024-04-23T21:15:46Z","modified":"2026-09-10T03:50:11.15128354Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:46:35.747385Z"},{"id":"UBUNTU-CVE-2024-31208","description":"Synapse is an open-source Matrix homeserver. A 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 the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.","status":"published","published":"2024-04-23T18:15:00Z","modified":"2026-10-17T12:56:35.141191607Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T16:54:48.333535Z"},{"id":"openSUSE-SU-2024:13897-1","title":"matrix-synapse-1.105.1-1.1 on GA media","description":"These are all security issues fixed in the matrix-synapse-1.105.1-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2024-06-15T00:00:00Z","modified":"2026-02-04T03:36:01.519198Z","updated_at":"2026-11-02T16:58:36.662953Z"},{"id":"PYSEC-2024-50","description":"Synapse is an open-source Matrix homeserver. A 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 the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.","status":"published","published":"2024-04-23T18:15:00Z","modified":"2024-04-23T21:56:31.264267Z","updated_at":"2026-11-02T15:52:54.242332Z"},{"id":"USN-7444-1","title":"matrix-synapse vulnerabilities","description":"It was discovered that Synapse network policies could be bypassed via\nspecially crafted URLs. An attacker could possibly use this issue to\nbypass authentication mechanisms. (CVE-2023-32683)\n\nIt was discovered that Synapse exposed cached device information. An\nattacker could possibly use this issue to gain access to sensitive\ninformation. (CVE-2023-43796)\n\nIt was discovered that Synapse could be tricked into rejecting state\nchanges in rooms. An attacker could possibly use this issue to cause\nSynapse to stop functioning properly, resulting in a denial of service.\nThis issue was only fixed in Ubuntu 20.04 LTS and Ubuntu 22.04 LTS.\n(CVE-2022-39374)\n\nIt was discovered that Synapse stored user credentials in a server's\ndatabase temporarily. An attacker could possibly use this issue to\ngain access to sensitive information. This issue was only fixed in\nUbuntu 22.04 LTS. (CVE-2023-41335)\n\nIt was discovered that Synapse could incorrectly respond to server\nauthorization events. An attacker could possibly use this issue to\nbypass authentication mechanisms. This issue was only fixed in Ubuntu\n22.04 LTS. (CVE-2022-39335)\n\nIt was discovered that Synapse could be manipulated to mark messages\nas read when they had not been viewed. An attacker could possibly use\nthis issue to perform repudiation-based attacks. This issue was only\nfixed in Ubuntu 22.04 LTS. (CVE-2023-42453)\n\nIt was discovered that Synapse had several memory-related issues. An\nattacker could possibly use this issue to cause Synapse to crash,\nresulting in a denial of service. This issue was only fixed in Ubuntu\n22.04 LTS. (CVE-2024-31208)\n\nIt was discovered that Synapse could run external tools due to a\nunchecked thumbnail rendering routine. An attacker could possibly use\nthis issue to cause Synapse to crash, resulting in a denial of service,\nor execute arbitrary code. This issue was only fixed in Ubuntu\n22.04 LTS. (CVE-2024-53863)\n","status":"published","published":"2025-04-22T17:24:26Z","modified":"2026-04-27T18:02:27.885669037Z","updated_at":"2026-11-02T16:58:19.988474Z"}]}}