CVE-2026-28732
MEDIUM 4.3Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 Fail to enforce slash command trigger-word uniqueness during command updates which allows an authenticated team member with Manage Own Slash Commands permission to hijack and impersonate existing system or custom slash commands via editing their own slash command trigger to an already-registered trigger through the command update API. Mattermost Advisory ID: MMSA-2026-00597
NO EXPLOITATION SIGNALS
No known exploitation, public exploit, or elevated probability at this time. Track for changes.
Exploitation likelihood
0.2%chance of exploitation in 30 days · 5th percentile
○ In CISA KEV
○ Public exploit / PoC
Impact if exploited
4.3CVSS 3.1 · MEDIUM
- ConfidentialityNone
- IntegrityLow
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ⚠Privileges: Requires a low-privilege account
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Weakness (CWE)
- CWE-863: Incorrect authorization
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N