{"id":"CVE-2023-43796","aliases":["ALPINE-CVE-2023-43796","DEBIAN-CVE-2023-43796","EUVD-2023-0136","GHSA-mp92-3jfm-3575","PYSEC-2023-230","UBUNTU-CVE-2023-43796","USN-7444-1","openSUSE-SU-2024:13392-1"],"status":"published","title":"Synapse vulnerable to leak of remote user device information","description":"Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.01196,"percentile":0.68349,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-200"],"published":"2023-10-31T16:52:48Z","modified":"2026-11-03T06:32:43Z","fixes":[{"ecosystem":"PyPI","package":"matrix-synapse","fixed_in":["1.95.1"],"sources":["ghsa","osv"]},{"ecosystem":"Alpine:v3.18","package":"synapse","fixed_in":["1.95.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.19","package":"synapse","fixed_in":["1.95.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.20","package":"synapse","fixed_in":["1.95.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.21","package":"synapse","fixed_in":["1.95.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.22","package":"synapse","fixed_in":["1.95.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.23","package":"synapse","fixed_in":["1.95.1-r0"],"sources":["osv"]},{"ecosystem":"Alpine:v3.24","package":"synapse","fixed_in":["1.95.1-r0"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:18.04:LTS","package":"matrix-synapse","fixed_in":["0.24.0+dfsg-1ubuntu0.1~esm4"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:20.04:LTS","package":"matrix-synapse","fixed_in":["1.11.0-1ubuntu0.1~esm2"],"sources":["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":["1.95.1-1.1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"matrix-synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.95.1"}]}]},{"source":"osv","ecosystem":"Alpine:v3.18","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.95.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.19","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.95.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.20","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.95.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.21","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.95.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.22","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.95.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.23","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.95.1-r0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.24","package":"synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.95.1-r0"}]}]},{"source":"osv","ecosystem":"PyPI","package":"matrix-synapse","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.95.1"}]}],"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","1.11.0","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"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List","web"]},{"url":"https://security.gentoo.org/glsa/202401-12","tags":["x_transferred","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-43796","tags":["advisory"]},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2023-230.yaml","tags":["web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2IDEEZMFJBDLTFHQUTZRJJNCOZGQ2ZVS","tags":["web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VH3RNC5ZPQZ4OKPSL4E6BBJSZOQLGDEY","tags":["web"]},{"url":"https://github.com/advisories/GHSA-mp92-3jfm-3575"},{"url":"https://security.alpinelinux.org/vuln/CVE-2023-43796","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/43xxx/CVE-2023-43796.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2023-43796","tags":["advisory"]},{"url":"https://github.com/matrix-org/synapse","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2023-43796","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2023-43796","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-2024-31208","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2024-53863","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2023-43796","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2023-43796","title":"Synapse vulnerable to leak of remote user device information","description":"Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.","status":"published","published":"2023-10-31T16:52:48.505Z","modified":"2025-02-13T17:13:30.615Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T14:35:14.298866Z"}],"euvd":[{"id":"EUVD-2023-0136","description":"Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.","status":"published","published":"2023-10-31T16:52:48Z","modified":"2025-02-13T17:13:30Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"updated_at":"2026-11-03T00:03:48.562419Z"}],"ghsa":[{"id":"GHSA-mp92-3jfm-3575","title":"Synapse vulnerable to leak of remote user device information","description":"### Impact\nCached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver.\n\n### Patches\nSystem administrators are encouraged to upgrade to Synapse 1.95.1 as soon as possible.\n\n### Workarounds\nThe `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.","status":"published","published":"2023-10-31T20:29:49Z","modified":"2025-02-13T19:21:03Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T14:38:31.416868Z"}],"nvd":[{"id":"CVE-2023-43796","description":"Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.","status":"published","published":"2023-10-31T17:15:23.27Z","modified":"2026-06-17T06:26:27.76Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T14:08:41.047232Z"}],"osv":[{"id":"ALPINE-CVE-2023-43796","description":"Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.","status":"published","published":"2023-10-31T17:15:23.27Z","modified":"2026-11-03T06:32:43.415659086Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"updated_at":"2026-11-03T07:17:02.90744Z"},{"id":"CVE-2023-43796","title":"Synapse vulnerable to leak of remote user device information","description":"Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.","status":"published","published":"2023-10-31T16:52:48.505Z","modified":"2026-10-28T02:30:30.326090949Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T15:44:33.792101Z"},{"id":"DEBIAN-CVE-2023-43796","description":"Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.","status":"withdrawn","published":"2023-10-31T17:15:23.27Z","modified":"2026-08-11T20:49:51.50270274Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T15:45:40.275853Z"},{"id":"GHSA-mp92-3jfm-3575","title":"Synapse vulnerable to leak of remote user device information","description":"### Impact\nCached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver.\n\n### Patches\nSystem administrators are encouraged to upgrade to Synapse 1.95.1 as soon as possible.\n\n### Workarounds\nThe `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.","status":"published","published":"2023-10-31T20:29:49Z","modified":"2026-09-10T03:49:24.728166201Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T15:46:52.170928Z"},{"id":"PYSEC-2023-230","description":"Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.\n","status":"published","published":"2023-10-31T17:15:00Z","modified":"2023-11-08T20:56:32.030692Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T15:52:53.837392Z"},{"id":"UBUNTU-CVE-2023-43796","description":"Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.","status":"published","published":"2023-10-31T17:15:00Z","modified":"2026-02-04T02:49:03.54433Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T16:54:22.741943Z"},{"id":"openSUSE-SU-2024:13392-1","title":"matrix-synapse-1.95.1-1.1 on GA media","description":"These are all security issues fixed in the matrix-synapse-1.95.1-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2024-06-15T00:00:00Z","modified":"2026-02-04T04:07:04.800017Z","updated_at":"2026-11-02T16:58:36.327643Z"},{"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"}]}}