Secuno
ENNL
Book demo

CVE-2025-12419

Mattermost Server vulnerability

9.9 CRITICALEPSS 0.34%
  1. Published27 Nov 2025

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 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredLow
User interactionNone
ScopeChanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected products

Mattermost Server≥ 10.11.0 < 10.11.5 · ≥ 10.12.0 < 10.12.2 · ≥ 10.5.0 < 10.5.13 · ≥ 11.0.0 < 11.0.4

Remediation

Fixed in
Mattermost Server≥ 10.11.5

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

CVE-2026-977209.1
Incorrect implementation of JWT/OAuth authentication in Impala executors in Apache…
CVE-2026-7724410.0
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products…
CVE-2026-734588.2
On affected platforms running Arista EOS with authenticated Bidirectional Forwarding…
CVE-2026-494678.8
Pingvin Share X is a secure and easy self-hosted file sharing platform. A vulnerability…
CVE-2026-100509.1
In Eclipse Jetty, the Digest authentication server-side component uses ISO-8859-1 to…
CVE-2026-593099.8
VMware vCenter contains an authentication bypass vulnerability in the VMware Directory…

Frequently asked

Is CVE-2025-12419 being actively exploited?

CVE-2025-12419 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.34%.

How severe is CVE-2025-12419?

CVE-2025-12419 has a CVSS 3.1 base score of 9.9, rated critical. EPSS estimates a 0.34% probability of exploitation.

Which products are affected by CVE-2025-12419?

Affected products include Mattermost Server.

How do I fix CVE-2025-12419?

Upgrade affected software to a fixed version, for example Mattermost Server 10.11.5 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-12419 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

See how prioritisation worksBook a demo

Get Patch this first every Monday

Five vulnerabilities that matter this week, ranked on real exploitation. Plain language, one email, no spam.

You can unsubscribe with one click from every issue. We handle your details as described in our privacy policy.

Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.