CVE-2026-28741: CSRF Protection Bypass Allows Updating a User's Authentication Method

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-15 · updated 2026-06-17
Weakness: CWE-352

Description

Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 11.4.x <= 11.4.2, 11.3.x <= 11.3.2 fail to validate CSRF tokens on an authentication endpoint which allows an attacker to update a user's authentication method via a CSRF attack by tricking a user into visiting a malicious page. Mattermost Advisory ID: MMSA-2026-00625

Affected products

Mattermost: from 10.11.0 before 10.11.13; from 11.3.0 before 11.3.3; from 11.4.0 before 11.4.3; from 11.5.0 before 11.5.1 — fixed in 10.11.13, 11.3.3, 11.4.3, 11.5.1

How to fix

Upgrade to a fixed version: Mattermost 10.11.13, 11.3.3, 11.4.3, 11.5.1. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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