{"id":"CVE-2026-25783","details":"Mattermost versions 11.3.x \u003c= 11.3.0, 11.2.x \u003c= 11.2.2, 10.11.x \u003c= 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","aliases":["GHSA-2v3w-6g35-5f9v","GO-2026-4725"],"modified":"2026-04-10T05:40:45.645489Z","published":"2026-03-16T14:18:23.593Z","related":["SUSE-SU-2026:1135-1"],"references":[{"type":"ADVISORY","url":"https://mattermost.com/security-updates"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/mattermost/mattermost-server","events":[{"introduced":"5b955468ea1ea8b56c0fb10feb258a36a767d7bb"},{"fixed":"fddd4a70bcb32eaff394a2fa5399efcd1b2ae251"},{"introduced":"ab7b138824c61fe1fe815243d7e2a914dec49c8b"},{"fixed":"005521aa79666e6960bc3302f6172b810f6bff3a"},{"introduced":"d27a2195068ddfa3ce17cf470f9739e4edb94b83"},{"fixed":"4082c3dcf285e4d1a386d2ef37f14f39dc5a0094"}],"database_specific":{"versions":[{"introduced":"10.11.0"},{"fixed":"10.11.11"},{"introduced":"11.2.0"},{"fixed":"11.2.3"},{"introduced":"11.3.0"},{"fixed":"11.3.1"}]}}],"versions":["@mattermost/client@10.11.0","@mattermost/client@11.3.0","@mattermost/types@10.11.0","@mattermost/types@11.3.0","mattermost-redux@10.11.0","mattermost-redux@11.3.0","v10.11.0","v10.11.0-rc3","v10.11.1","v10.11.1-rc1","v10.11.10","v10.11.11-rc1","v10.11.2","v10.11.2-rc1","v10.11.2-rc2","v10.11.3","v10.11.4","v10.11.4-rc1","v10.11.4-rc2","v10.11.4-rc3","v10.11.5","v10.11.6","v10.11.7","v10.11.8","v10.11.9","v10.11.9-rc1","v11.2.0","v11.2.1","v11.2.1-rc1","v11.2.2","v11.3.0","v11.3.0-rc3","v11.3.0-rc4","v11.3.1-rc1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-25783.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L"}]}