CVE-2026-6961
HIGH 7.6Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 Mattermost fails to sanitize FileInfo.Name received from federated peers during shared channel file sync, which allows an attacker who controls a federated server to write files to arbitrary locations within the target server's filestore via path traversal sequences in the filename field.. Mattermost Advisory ID: MMSA-2026-00661
ELEVATED IMPACT
Severe if exploited (CVSS 7.6), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.3%chance of exploitation in 30 days · 21st percentile
○ In CISA KEV
○ Public exploit / PoC
Impact if exploited
7.6CVSS 3.1 · HIGH
- ConfidentialityNone
- IntegrityHigh
- AvailabilityLow
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ⚠Privileges: Requires an admin / high-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-22: Path traversal
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:L