VULNERABILITY INTELLIGENCE

CVE-2026-12985

CVSS score6.8 MEDIUM
EPSS probability0.27%
CISA KEVNot currently listed
Published2026-09-14
Last modified2026-10-07
CVSS vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

Description

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 Mattermost failed to validate Dynamic Client Registration redirect URIs by URL component (matching glob patterns against the raw URI string instead) which allows a remote unauthenticated attacker to register an OAuth client with an attacker-controlled callback host that bypasses the configured redirect URI allowlist via a crafted redirect URI that places an allowlisted host/path suffix inside the query string.. Mattermost Advisory ID: MMSA-2026-00700

Weakness classification

  • responsibledisclosure@mattermost.com: CWE-601

Primary references