Critical severity · published Nov 27, 2025
CVE-2025-12419
Account takeover on OAuth/OpenID-enabled servers
9.9
CVSS
0.4%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 30% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
Mattermost · Mattermost
10.12.0 through 10.12.1; 10.11.0 through 10.11.4; 10.5.0 through 10.5.12; 11.0.0 through 11.0.3 · source: vendor
MS
Mattermost Server · Mattermost
10.5.0 before 10.5.13; 10.11.0 before 10.11.5; 10.12.0 before 10.12.2; 11.0.0 before 11.0.4 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-12419
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-12419
Vendor Advisory
https://mattermost.com/security-updates
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