Mattermost OAuth State Validation Flaw, Account Takeover in 10.x and 11.0.x
CVE-2025-12419 Published on November 27, 2025
Account takeover on OAuth/OpenID-enabled servers
Mattermost versions 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12, 11.0.x <= 11.0.3 fail to properly validate OAuth state tokens during OpenID Connect authentication which allows an authenticated attacker with team creation privileges to take over a user account via manipulation of authentication data during the OAuth completion flow. This requires email verification to be disabled (default: disabled), OAuth/OpenID Connect to be enabled, and the attacker to control two users in the SSO system with one of them never having logged into Mattermost.
Vulnerability Analysis
CVE-2025-12419 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.
Weakness Type
Incorrect Implementation of Authentication Algorithm
The requirements for the software dictate the use of an established authentication algorithm, but the implementation of the algorithm is incorrect. This incorrect implementation may allow authentication to be bypassed.
Products Associated with CVE-2025-12419
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Affected Versions
Mattermost:- Version 10.12.0, <= 10.12.1 is affected.
- Version 10.11.0, <= 10.11.4 is affected.
- Version 10.5.0, <= 10.5.12 is affected.
- Version 11.0.0, <= 11.0.3 is affected.
- Version 11.1.0 is unaffected.
- Version 10.12.2 is unaffected.
- Version 10.11.5 is unaffected.
- Version 10.5.13 is unaffected.
- Version 11.0.4 is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.