CVE-2025-12419
CVE-2025-12419 is a critical-severity vulnerability in Mattermost Mattermost Server with a CVSS 3.x base score of 9.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-303.
Key facts
- Severity: Critical (CVSS 3.x base score 9.9)
- EPSS exploit prediction: 0% (23rd percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-199827
- Weakness: CWE-303
- Affected product: Mattermost Mattermost Server
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2025-12419?
- 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.
- How severe is CVE-2025-12419?
- CVE-2025-12419 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2025-12419 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2025-12419?
- CVE-2025-12419 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2025-12419?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- Does CVE-2025-12419 have an EU (EUVD) identifier?
- Yes. CVE-2025-12419 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-199827.
- When was CVE-2025-12419 published?
- CVE-2025-12419 was published on 2025-11-27 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
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- CVE-2025-20051 — Critical (CVSS 9.9): Mattermost versions 10.4.x <= 10.4.1, 9.11.x <= 9.11.7, 10.3.x <= 10.3.2, 10.2.x <= 10.2.2 fail to properly validate…
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- CVE-2017-18915 — Critical (CVSS 9.8): An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. After a restart of a server, an attacker…
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