🛡️ CVE-2025-12421
🔴 CVSS 9.9 — Critical ✅ No Known Exploit CWE-287 NVD
9.9
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to to verify that the token used during the code exchange originates from the same authentication flow, which allows an authenticated user to perform account takeover via a specially crafted email address used when switching authentication methods and sending a request to the /users/login/sso/code-exchange endpoint. The vulnerability requires ExperimentalEnableAuthenticationTransfer to be enabled (default: enabled) and RequireEmailVerification to be disabled (default: disabled).

Details

Severity CRITICAL
CVSS Score 9.9
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CWE CWE-287
Public Exploit ✅ No
Source NVD
Published 2025-11-27
Updated 2026-06-15
Modified 2025-12-15
Fix URL N/A

Affected Packages

Software From version Fixed in
github.com/mattermost/mattermost-server — —
github.com/mattermost/mattermost-server/v5 — —
github.com/mattermost/mattermost-server/v6 — —
github.com/mattermost/mattermost/server/v8 — —
mattermost-server 11.0.0 11.0.3

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