Slash command trigger-word update allowed command hijacking
Priority LOW 19CWE-863Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-863.
Summary
Mattermost versions 11.5.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
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00152 4th percentileScored 2026-11-07
Fix Fixed Mattermost (Mattermost): 11.6.0, 11.5.2, 10.11.14 +1github.com/mattermost/mattermost/server/v8 (Go): 11.5.2, 10.11.14, 11.4.4 +1+1 more product
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 | 11.5.0 – 11.5.1; 10.11.0 – 10.11.13; 11.4.0 – 11.4.3 | 11.6.0, 11.5.2, 10.11.14, 11.4.4 | Patch available | CNA |
| — | github.com/mattermost/mattermost/server/v8 (Go) | 11.5.0 to before 11.5.2 | 11.5.2 | Patch available | GHSA-wvcv-9xpm-7mqc |
| — | github.com/mattermost/mattermost/server/v8 (Go) | 10.11.0 to before 10.11.14 | 10.11.14 | Patch available | GHSA-wvcv-9xpm-7mqc |
| — | github.com/mattermost/mattermost/server/v8 (Go) | 11.4.0 to before 11.4.4 | 11.4.4 | Patch available | GHSA-wvcv-9xpm-7mqc |
| — | github.com/mattermost/mattermost/server/v8 (Go) | before 8.0.0-20260306123948-f5fe8ded6b63 | 8.0.0-20260306123948-f5fe8ded6b63 | Patch available | GHSA-wvcv-9xpm-7mqc |
| — | github.com/mattermost/mattermost-server (Go) | before 5.3.2-0.20260306123948-f5fe8ded6b63 | 5.3.2-0.20260306123948-f5fe8ded6b63 | Patch available | GHSA-wvcv-9xpm-7mqc |
- Mattermost VendorMattermost Affected 11.5.0 – 11.5.1; 10.11.0 – 10.11.13; 11.4.0 – 11.4.3 Fixed in 11.6.0, 11.5.2, 10.11.14, 11.4.4 Patch available CNA
- github.com/mattermost/mattermost/server/v8 (Go) Vendor— Affected 11.5.0 to before 11.5.2 Fixed in 11.5.2 Patch available GHSA-wvcv-9xpm-7mqc
- github.com/mattermost/mattermost/server/v8 (Go) Vendor— Affected 10.11.0 to before 10.11.14 Fixed in 10.11.14 Patch available GHSA-wvcv-9xpm-7mqc
- github.com/mattermost/mattermost/server/v8 (Go) Vendor— Affected 11.4.0 to before 11.4.4 Fixed in 11.4.4 Patch available GHSA-wvcv-9xpm-7mqc
- github.com/mattermost/mattermost/server/v8 (Go) Vendor— Affected before 8.0.0-20260306123948-f5fe8ded6b63 Fixed in 8.0.0-20260306123948-f5fe8ded6b63 Patch available GHSA-wvcv-9xpm-7mqc
- github.com/mattermost/mattermost-server (Go) Vendor— Affected before 5.3.2-0.20260306123948-f5fe8ded6b63 Fixed in 5.3.2-0.20260306123948-f5fe8ded6b63 Patch available GHSA-wvcv-9xpm-7mqc
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* | 10.11.0 to before 10.11.14; 11.4.0 to before 11.4.4; 11.5.0 to before 11.5.2 | Vulnerable | Mattermost |
- cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* Versions 10.11.0 to before 10.11.14; 11.4.0 to before 11.4.4; 11.5.0 to before 11.5.2 Vulnerable ·Mattermost
Remediation
- Fix · CNA Mattermost (Mattermost) Fixed in 11.6.0, 11.5.2, 10.11.14, 11.4.4
- Fix · GHSA-wvcv-9xpm-7mqc github.com/mattermost/mattermost/server/v8 (Go) Fixed in 11.5.2 Advisory →
- Fix · GHSA-wvcv-9xpm-7mqc github.com/mattermost/mattermost/server/v8 (Go) Fixed in 10.11.14 Advisory →
- Fix · GHSA-wvcv-9xpm-7mqc github.com/mattermost/mattermost/server/v8 (Go) Fixed in 11.4.4 Advisory →
- Fix · GHSA-wvcv-9xpm-7mqc github.com/mattermost/mattermost/server/v8 (Go) Fixed in 8.0.0-20260306123948-f5fe8ded6b63 Advisory →
- Fix · GHSA-wvcv-9xpm-7mqc github.com/mattermost/mattermost-server (Go) Fixed in 5.3.2-0.20260306123948-f5fe8ded6b63 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-28732
- 2026-10-03 Alias added: GHSA-wvcv-9xpm-7mqc
References
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-2026-28732 · CVE Program
- CVE-2026-28732 · NVD
- FIRST EPSS
- GHSA-wvcv-9xpm-7mqc · 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