Description
Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to verify the integrity of the SAML RelayState POST parameter which allows an authenticated SAML user to join any team, including invite-only teams, via forging the team_id or invite_id fields in the RelayState.. Mattermost Advisory ID: MMSA-2026-00727
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 11.10.0 – ≤ 11.10.0, 11.7.0 – ≤ 11.7.9, 11.9.0 – ≤ 11.9.1, 11.8.0 – ≤ 11.8.5 | 11.11.0 |
Advisories 1
- WID-SEC-2026-4009 Mattermost: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 15, 2026
References
- MMSA-2026-00727 vendor-advisory