Ordinary group/direct message member can enable group_constrained and remove all channel participants
Priority LOW 24CWE-862Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- None · Low · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-862.
Summary
Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to restrict the group_constrained channel flag to public and private channels that support group synchronization, which allows an ordinary group or direct message member to remove all participants from the conversation via the channel patch API.. Mattermost Advisory ID: MMSA-2026-00688
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00287 21st percentileScored 2026-11-08
Fix Fixed Mattermost (Mattermost): 11.8.0, 11.7.3, 11.6.5 +1
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Mattermost | Mattermost | 11.7.0 – 11.7.2; 11.6.0 – 11.6.4; 10.11.0 – 10.11.19 | 11.8.0, 11.7.3, 11.6.5, 10.11.20 | Patch available | CNA |
- Mattermost VendorMattermost Affected 11.7.0 – 11.7.2; 11.6.0 – 11.6.4; 10.11.0 – 10.11.19 Fixed in 11.8.0, 11.7.3, 11.6.5, 10.11.20 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* | 10.11.0 to before 10.11.20; 11.6.0 to before 11.6.5; 11.7.0 to before 11.7.3 | Vulnerable | Mattermost |
- cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* Versions 10.11.0 to before 10.11.20; 11.6.0 to before 11.6.5; 11.7.0 to before 11.7.3 Vulnerable ·Mattermost
Remediation
- Fix · CNA Mattermost (Mattermost) Fixed in 11.8.0, 11.7.3, 11.6.5, 10.11.20
Timeline
- 2026-10-02 Threatist record created from CVE-2026-10085
- 2026-10-03 Alias added: GHSA-6v2h-jj3h-8gmx
References
Advisory 1
More Mattermost Server vulnerabilities
- TI-2025-18933 Arbitrary file read in Mattermost Boards via import & export board archive CVSS 3.1CRITICAL 9.9
- TI-2025-04465 Path Traversal Leading to RCE by Any Authenticated Mattermost User CVSS 3.1CRITICAL 9.9
- TI-2017-14068 An issue was discovered in Mattermost Server before 3.6.2. CVSS 3.1CRITICAL 9.8
- TI-2017-14060 An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. CVSS 3.1CRITICAL 9.8
- TI-2017-14048 An issue was discovered in Mattermost Server before 4.1.0, 4.0.4, and 3.10.3. CVSS 3.1CRITICAL 9.8
- TI-2025-14360 Arbitrary file read via block duplication in Mattermost Boards CVSS 3.1CRITICAL 9.9
Sources
- CVE-2026-10085 · CVE Program
- CVE-2026-10085 · NVD
- FIRST EPSS
- GHSA-6v2h-jj3h-8gmx · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences