CVE-2025-58075: Arbitrary Mattermost Team can be joined by manipulating the SAML RelayState

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-10-16 · updated 2026-10-19
Weakness: CWE-862

Description

Mattermost versions 10.11.x <= 10.11.1, 10.10.x <= 10.10.2, 10.5.x <= 10.5.10 fail to verify a user has permission to join a Mattermost team using the original invite token which allows any attacked to join any team on a Mattermost server regardless of restrictions via manipulating the RelayState

Affected products

Mattermost: from 10.5.0 before 10.5.11; from 10.10.0 before 10.10.3; from 10.11.0 before 10.11.3 — fixed in 10.10.3, 10.11.3, 10.5.11

How to fix

Upgrade to a fixed version: Mattermost 10.10.3, 10.11.3, 10.5.11. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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