CVE-2026-18799
CVE-2026-18799 · Mattermost Server fails to restrict Slack import account binding, allowing team admins to forge posts as existing users
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 restrict Slack import account binding to system administrator-initiated imports which allows an authenticated attacker with team admin privileges to force-add existing Mattermost users to their team and forge posts attributed to those users' identities via a crafted Slack export containing target users' email addresses.. Mattermost Advisory ID: MMSA-2026-00757
CVSS 4.3 · 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