Mattermost group syncable endpoints allow privilege escalation via scheme_admin
Priority MEDIUM 40CWE-863Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-863.
Summary
Mattermost 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 require role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints, which allows a user with group-link permissions to escalate themselves and group members to team or channel admin via crafted API requests.. Mattermost Advisory ID: MMSA-2026-00665
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0031 23rd percentileScored 2026-11-07
Fix Fixed Mattermost (Mattermost): 11.7.0, 11.6.2, 11.5.5 +2github.com/mattermost/mattermost-server (Go): 11.6.1, 11.5.5, 10.11.17+1 more product
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
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 | 11.6.0 – 11.6.1; 11.5.0 – 11.5.4; 10.11.0 – 10.11.15; 10.11.0 – 10.11.16 | 11.7.0, 11.6.2, 11.5.5, 10.11.16, 10.11.17 | Patch available | CNA |
| — | github.com/mattermost/mattermost-server (Go) | 11.6.0 to before 11.6.1 | 11.6.1 | Patch available | GHSA-6hxm-w4hv-vgvw |
| — | github.com/mattermost/mattermost-server (Go) | 11.5.0 to before 11.5.5 | 11.5.5 | Patch available | GHSA-6hxm-w4hv-vgvw |
| — | github.com/mattermost/mattermost-server (Go) | 10.11.0 to before 10.11.17 | 10.11.17 | Patch available | GHSA-6hxm-w4hv-vgvw |
| — | github.com/mattermost/mattermost/server/v8 (Go) | 8.0.0-20250731163400-5b955468ea1e to before 8.0.0-20260506065351-202d125afa87 | 8.0.0-20260506065351-202d125afa87 | Patch available | GHSA-6hxm-w4hv-vgvw |
- Mattermost VendorMattermost Affected 11.6.0 – 11.6.1; 11.5.0 – 11.5.4; 10.11.0 – 10.11.15; 10.11.0 – 10.11.16 Fixed in 11.7.0, 11.6.2, 11.5.5, 10.11.16, 10.11.17 Patch available CNA
- github.com/mattermost/mattermost-server (Go) Vendor— Affected 11.6.0 to before 11.6.1 Fixed in 11.6.1 Patch available GHSA-6hxm-w4hv-vgvw
- github.com/mattermost/mattermost-server (Go) Vendor— Affected 11.5.0 to before 11.5.5 Fixed in 11.5.5 Patch available GHSA-6hxm-w4hv-vgvw
- github.com/mattermost/mattermost-server (Go) Vendor— Affected 10.11.0 to before 10.11.17 Fixed in 10.11.17 Patch available GHSA-6hxm-w4hv-vgvw
- github.com/mattermost/mattermost/server/v8 (Go) Vendor— Affected 8.0.0-20250731163400-5b955468ea1e to before 8.0.0-20260506065351-202d125afa87 Fixed in 8.0.0-20260506065351-202d125afa87 Patch available GHSA-6hxm-w4hv-vgvw
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* | 10.11.0 to before 10.11.17; 11.5.0 to before 11.5.5; 11.6.0 to before 11.6.2 | Vulnerable | Mattermost |
- cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* Versions 10.11.0 to before 10.11.17; 11.5.0 to before 11.5.5; 11.6.0 to before 11.6.2 Vulnerable ·Mattermost
Remediation
- Fix · CNA Mattermost (Mattermost) Fixed in 11.7.0, 11.6.2, 11.5.5, 10.11.16, 10.11.17
- Fix · GHSA-6hxm-w4hv-vgvw github.com/mattermost/mattermost-server (Go) Fixed in 11.6.1 Advisory →
- Fix · GHSA-6hxm-w4hv-vgvw github.com/mattermost/mattermost-server (Go) Fixed in 11.5.5 Advisory →
- Fix · GHSA-6hxm-w4hv-vgvw github.com/mattermost/mattermost-server (Go) Fixed in 10.11.17 Advisory →
- Fix · GHSA-6hxm-w4hv-vgvw github.com/mattermost/mattermost/server/v8 (Go) Fixed in 8.0.0-20260506065351-202d125afa87 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-7387
- 2026-10-03 Alias added: GHSA-6hxm-w4hv-vgvw
References
Other 15
- https://github.com/mattermost/mattermost/pull/36434
- https://github.com/mattermost/mattermost/pull/36432
- https://github.com/mattermost/mattermost/pull/36431
- https://github.com/mattermost/mattermost/pull/36423
- https://github.com/mattermost/mattermost/pull/36316
- https://github.com/mattermost/mattermost/commit/d5f29c8ebbeb04460d16d9e2635ce50deeb78428
- https://github.com/mattermost/mattermost/commit/a9e574a82633915f22071f0d7ca2b006f249ec2a
- https://github.com/mattermost/mattermost/commit/8c72083414e675c97987374395e36d1f36b4bd8a
- https://github.com/mattermost/mattermost/commit/202d125afa87fe39611686850fd82590c99ca344
- https://github.com/mattermost/mattermost/commit/1ce2484a00c9821ee19708d2c46720e4855033a9
- https://github.com/mattermost/mattermost/releases/tag/v10.11.16
- https://github.com/mattermost/mattermost/releases/tag/v11.5.5
- https://github.com/mattermost/mattermost/releases/tag/v11.6.2
- https://github.com/mattermost/mattermost/releases/tag/v11.7.0
- https://github.com/mattermost/mattermost
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-2026-7387 · CVE Program
- CVE-2026-7387 · NVD
- FIRST EPSS
- GHSA-6hxm-w4hv-vgvw · 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