CVE-2025-12421

critical · 9.9

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).

9.9

CVSS

0.3%

EPSS (exploit prob.)

28th

EPSS percentile

2025-11-27

Published

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Weaknesses

CWE-303

Affected products

Vendor	Product	Affected versions
mattermost	mattermost_server	>= 10.5.0, < 10.5.13
mattermost	mattermost_server	>= 10.11.0, < 10.11.5
mattermost	mattermost_server	>= 10.12.0, < 10.12.2
mattermost	mattermost_server	>= 11.0.0, < 11.0.3

Check a specific version with /api/v1/cve/match.

References

https://mattermost.com/security-updates

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2025-12421