{"schema_version":"1.9.0","id":"CVE-2026-25783","published":"2026-03-16T12:04:18.478Z","modified":"2026-08-12T03:51:12.471475284Z","aliases":["GHSA-2v3w-6g35-5f9v","GO-2026-4725"],"related":["SUSE-SU-2026:1135-1","openSUSE-SU-2026:21483-1"],"summary":"Denial of service via malformed User-Agent header in getBrowserVersion","details":"Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly validate User-Agent header tokens which allows an authenticated attacker to cause a request panic via a specially crafted User-Agent header. Mattermost Advisory ID: MMSA-2026-00586","affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/mattermost/mattermost","events":[{"introduced":"5b955468ea1ea8b56c0fb10feb258a36a767d7bb"},{"fixed":"fddd4a70bcb32eaff394a2fa5399efcd1b2ae251"},{"introduced":"ab7b138824c61fe1fe815243d7e2a914dec49c8b"},{"fixed":"005521aa79666e6960bc3302f6172b810f6bff3a"},{"introduced":"d27a2195068ddfa3ce17cf470f9739e4edb94b83"},{"fixed":"4082c3dcf285e4d1a386d2ef37f14f39dc5a0094"}],"database_specific":{"cpe":"cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"10.11.0"},{"fixed":"10.11.11"},{"introduced":"11.2.0"},{"fixed":"11.2.3"},{"introduced":"11.3.0"},{"fixed":"11.3.1"}],"source":"CPE_RANGE"}}],"versions":["v10.11.11-rc1","v11.3.1-rc1","v10.11.10","v11.2.2","v11.3.0-rc4","v11.3.0-rc3","v11.3.0","mattermost-redux@11.3.0","@mattermost/types@11.3.0","@mattermost/client@11.3.0","v10.11.9","v11.2.1","v11.2.1-rc1","v11.2.0","v10.11.9-rc1","v10.11.8","v10.11.7","v10.11.6","v10.11.5","v10.11.4-rc3","v10.11.4","v10.11.4-rc2","v10.11.4-rc1","v10.11.3","v10.11.2-rc2","v10.11.2","v10.11.2-rc1","v10.11.1","v10.11.1-rc1","v10.11.0-rc3","v10.11.0","mattermost-redux@10.11.0","@mattermost/types@10.11.0","@mattermost/client@10.11.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-25783.json"}}],"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25783.json"},{"type":"ADVISORY","url":"https://mattermost.com/security-updates"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-25783"}],"database_specific":{"cna_assigner":"Mattermost","cwe_ids":["CWE-1287"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25783.json","unresolved_ranges":[{"extracted_events":[{"introduced":"11.3.0"},{"last_affected":"11.3.0"},{"introduced":"11.2.0"},{"last_affected":"11.2.2"},{"introduced":"10.11.0"},{"last_affected":"10.11.10"}],"source":"AFFECTED_FIELD"}]},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L"}]}