CVE-2025-6227: Invite token is used as part of the secure communication

Severity: low (CVSS 3.1 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: 2025-07-18 · updated 2026-06-17
Weakness: CWE-522

Description

Mattermost versions 10.5.x <= 10.5.7, 9.11.x <= 9.11.16 fail to negotiate a new token when accepting the invite which allows a user that intercepts both invite and password to send synchronization payloads to the server that originally created the invite via the REST API.

Affected products

Mattermost: from 9.11.0 before 9.11.17; from 10.5.0 before 10.5.8 — fixed in 10.5.8, 9.11.17

How to fix

Upgrade to a fixed version: Mattermost 10.5.8, 9.11.17. Check the vendor advisory for mitigations.

References

https://mattermost.com/security-updates

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