Mattermost Jira plugin had unauthenticated {{/ac/installed}} lifecycle callback during pending Jira Cloud install
Priority LOW 28CWE-306Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- Required
- Attack complexity
- High
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- None · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-306.
Summary
Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00299 22nd percentileScored 2026-11-07
Fix Fixed Mattermost (Mattermost): 11.8.0, 11.7.1, 11.6.3 +2github.com/mattermost/mattermost-server (Go): 11.7.1, 11.6.3, 11.5.6 +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 – 11.7.0; 11.6.0 – 11.6.2; 11.5.0 – 11.5.5; 10.11.0 – 10.11.17 | 11.8.0, 11.7.1, 11.6.3, 11.5.6, 10.11.18 | Patch available | CNA |
| — | github.com/mattermost/mattermost-server (Go) | 11.7.0 to before 11.7.1 | 11.7.1 | Patch available | GHSA-jqgv-39mg-7c2r |
| — | github.com/mattermost/mattermost-server (Go) | 11.6.0 to before 11.6.3 | 11.6.3 | Patch available | GHSA-jqgv-39mg-7c2r |
| — | github.com/mattermost/mattermost-server (Go) | 11.5.0 to before 11.5.6 | 11.5.6 | Patch available | GHSA-jqgv-39mg-7c2r |
| — | github.com/mattermost/mattermost-server (Go) | 10.11.0 to before 10.11.18 | 10.11.18 | Patch available | GHSA-jqgv-39mg-7c2r |
- Mattermost VendorMattermost Affected 11.7.0 – 11.7.0; 11.6.0 – 11.6.2; 11.5.0 – 11.5.5; 10.11.0 – 10.11.17 Fixed in 11.8.0, 11.7.1, 11.6.3, 11.5.6, 10.11.18 Patch available CNA
- github.com/mattermost/mattermost-server (Go) Vendor— Affected 11.7.0 to before 11.7.1 Fixed in 11.7.1 Patch available GHSA-jqgv-39mg-7c2r
- github.com/mattermost/mattermost-server (Go) Vendor— Affected 11.6.0 to before 11.6.3 Fixed in 11.6.3 Patch available GHSA-jqgv-39mg-7c2r
- github.com/mattermost/mattermost-server (Go) Vendor— Affected 11.5.0 to before 11.5.6 Fixed in 11.5.6 Patch available GHSA-jqgv-39mg-7c2r
- github.com/mattermost/mattermost-server (Go) Vendor— Affected 10.11.0 to before 10.11.18 Fixed in 10.11.18 Patch available GHSA-jqgv-39mg-7c2r
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* | 10.11.0 to before 10.11.18; 11.5.0 to before 11.5.6; 11.6.0 to before 11.6.3; 11.7.0 to before 11.7.1 | Vulnerable | Mattermost |
- cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* Versions 10.11.0 to before 10.11.18; 11.5.0 to before 11.5.6; 11.6.0 to before 11.6.3; 11.7.0 to before 11.7.1 Vulnerable ·Mattermost
Remediation
- Fix · CNA Mattermost (Mattermost) Fixed in 11.8.0, 11.7.1, 11.6.3, 11.5.6, 10.11.18
- Fix · GHSA-jqgv-39mg-7c2r github.com/mattermost/mattermost-server (Go) Fixed in 11.7.1 Advisory →
- Fix · GHSA-jqgv-39mg-7c2r github.com/mattermost/mattermost-server (Go) Fixed in 11.6.3 Advisory →
- Fix · GHSA-jqgv-39mg-7c2r github.com/mattermost/mattermost-server (Go) Fixed in 11.5.6 Advisory →
- Fix · GHSA-jqgv-39mg-7c2r github.com/mattermost/mattermost-server (Go) Fixed in 10.11.18 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-6673
- 2026-10-03 Alias added: GHSA-jqgv-39mg-7c2r
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-2026-6673 · CVE Program
- CVE-2026-6673 · NVD
- FIRST EPSS
- GHSA-jqgv-39mg-7c2r · GitHub Advisory Database · CC BY 4.0
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