Description
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
Metrics
CVSS 3.1 4.3/10
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:LWeakness enumeration
Affected software
No affected versions have been published.
Timeline
- Published
- Mar 16, 2026
- Last modified
- Jun 17, 2026
- NVD status
- Analyzed