CVE-2026-18551
CVE-2026-18551 · Mattermost guest account privilege escalation via member roles API
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 validate the combination of guest and admin scheme roles which allows an authenticated attacker to escalate a guest account to team or channel admin via a crafted PUT request to the member roles API endpoint.. Mattermost Advisory ID: MMSA-2026-00752
CVSS 6.5 · Medium · EPSS 0.2%
- 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
No fix published