GitLab Plugin Allows Non-Admin Users to Modify Default Instance Configuration
Summary
| CVE | CVE-2026-5139 |
|---|---|
| State | PUBLISHED |
| Assigner | Mattermost |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-06-22 14:17:50 UTC |
| Updated | 2026-06-23 20:50:51 UTC |
| Description | 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 enforce administrator authorization on the {{setDefaultInstance}} call within the {{/gitlab connect}} command handler, which allows any authenticated user to overwrite the global default GitLab instance configuration via the {{/gitlab connect <instance-name>}} slash command.. Mattermost Advisory ID: MMSA-2026-00644 |
Risk And Classification
Primary CVSS: v3.1 5.4 MEDIUM from [email protected]
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
EPSS: 0.001700000 probability, percentile 0.065940000 (date 2026-06-25)
Problem Types: CWE-862 | CWE-862 CWE-862: Missing Authorization
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 5.4 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L |
| 3.1 | CNA | CVSS | 5.4 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
LowUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
LowAvailability
LowCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Mattermost | Mattermost Server | All | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Mattermost | Mattermost | affected 11.7.0 11.7.0 semver | Not specified |
| CNA | Mattermost | Mattermost | affected 11.6.0 11.6.2 semver | Not specified |
| CNA | Mattermost | Mattermost | affected 11.5.0 11.5.5 semver | Not specified |
| CNA | Mattermost | Mattermost | affected 10.11.0 10.11.17 semver | Not specified |
| CNA | Mattermost | Mattermost | unaffected 11.8.0 | Not specified |
| CNA | Mattermost | Mattermost | unaffected 11.7.1 | Not specified |
| CNA | Mattermost | Mattermost | unaffected 11.6.3 | Not specified |
| CNA | Mattermost | Mattermost | unaffected 11.5.6 | Not specified |
| CNA | Mattermost | Mattermost | unaffected 10.11.18 | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| mattermost.com/security-updates | [email protected] | mattermost.com | Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: hunterxluxhug (en)
Additional Advisory Data
Solutions
CNA: Update Mattermost to versions 11.8.0, 11.7.1, 11.6.3, 11.5.6, 10.11.18 or higher.
There are currently no legacy QID mappings associated with this CVE.