CVE-2025-13324: Lack of Invalidation of Legacy Remote Cluster Invite Tokens After Confirmation

Severity: low (CVSS 3.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-12-17 · updated 2026-10-13
Weakness: CWE-863

Description

Mattermost versions 10.11.x <= 10.11.5, 11.0.x <= 11.0.4, 10.12.x <= 10.12.2 fail to invalidate remote cluster invite tokens when using the legacy (version 1) protocol or when the confirming party does not provide a refreshed token, which allows an attacker who has obtained an invite token to authenticate as the remote cluster and perform limited actions on shared channels even after the invitation has been legitimately confirmed.

Affected products

Mattermost: from 10.11.0 before 10.11.6; from 10.12.0 before 10.12.3; from 11.0.0 before 11.0.5 — fixed in 10.11.6, 10.12.3, 11.0.5

How to fix

Upgrade to a fixed version: Mattermost 10.11.6, 10.12.3, 11.0.5. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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