CVE-2026-25783CWE-1287

Denial of service via malformed User-Agent header in getBrowserVersion

Medium · published March 16, 2026

CVSS v3.1
4.3
EPSS
0%
Percentile
30.9
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
4.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
CVSS v4.0
Not supplied
EPSS
0.00382 · 30.9th percentile
Weakness
CWE-1287 · Improper Validation of Specified Type of Input
Published
2026-03-16T12:04Z
EPSS history
Timeline
  • 16 MAR 12:04Z
    Denial of service via malformed User-Agent header in getBrowserVersion
    cvelistv5