SecuriTricks - CVE-2025-12421

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).

Product(s) Impacted

Vendor	Product	Versions
Mattermost	Mattermost	11.0., 10.12., 10.11., 10.5.

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-303

Incorrect Implementation of Authentication Algorithm

The requirements for the product dictate the use of an established authentication algorithm, but the implementation of the algorithm is incorrect.

*CPE(s)

Affected systems and software identified for this CVE.

Type	Vendor	Product	Version	Update	Edition	Language	Software Edition	Target Software	Target Hardware	Other Information
a	mattermost	mattermost	11.0.*	/	/	/	/	/	/	/
a	mattermost	mattermost	10.12.*	/	/	/	/	/	/	/
a	mattermost	mattermost	10.11.*	/	/	/	/	/	/	/
a	mattermost	mattermost	10.5.*	/	/	/	/	/	/	/

References

https://mattermost.com/security-updates

CVSS Score

9.9 / 10

CVSS Data - 3.1

Attack Vector: NETWORK
Attack Complexity: LOW
Privileges Required: LOW
Scope: CHANGED
Confidentiality Impact: HIGH
Integrity Impact: HIGH
Availability Impact: HIGH

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

View Vector String

Timeline

Published: Nov. 27, 2025, 6:15 p.m.
Last Modified: Nov. 28, 2025, 11:11 p.m.

Status : Undergoing Analysis

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

responsibledisclosure@mattermost.com

CVE-2025-12421