CVE-2026-16453
CVE-2026-16453 · Mattermost SAML RelayState forgery allows unauthorized team membership
This page contains facts from public vulnerability sources. Check the original advisory before updating.
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
CVSS 7.1 · High · EPSS 0.2% · Fix available
- Published
- Updated
Affected products and versions
mattermost
- Versions
- ≥ 11.10.0, ≤ 11.10.0: Affected (semver)
- ≥ 11.7.0, ≤ 11.7.9: Affected (semver)
- ≥ 11.9.0, ≤ 11.9.1: Affected (semver)
- ≥ 11.8.0, ≤ 11.8.5: Affected (semver)
- 11.11.0: Not affected
- 11.10.1: Not affected
- 11.7.10: Not affected
- 11.9.2: Not affected
- 11.8.6: Not affected
Update to 11.10.1; Update to 11.7.10; Update to 11.8.6; Update to 11.9.2