CVE-2026-6739Mattermost: Delegated admins could patch protected default system roles
- 6.7MediumCVSS base score
- 0.26%Exploitation in 30 daysEPSS · top 82% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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 fail to require system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions to escalate privileges by altering built-in role permissions via the role patch API.. Mattermost Advisory ID: MMSA-2026-00656
Timeline
ID reserved
By Mattermost
- 52 days later
· 52 days later
Published
- 1 day later
· 1 day later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| MattermostCNA (assigner) | 3.1 | Medium6.7 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L |
| NVDNVD · Analyzed | 3.1 | High7.2 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.26% · top 82% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.7.
Affected products
- affected 11.6.0 – ≤ 11.6.1
- affected 11.5.0 – ≤ 11.5.4
- affected 10.11.0 – ≤ 10.11.15
- affected 10.11.0 – ≤ 10.11.16
- unaffected 11.7.0
- unaffected 11.6.2
- unaffected 11.5.5
- unaffected 10.11.16
- unaffected 10.11.17
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Gogithub.com/mattermost/mattermost-serverGHSA-m2w9-h2mm-79qr (opens in a new tab)
- Gogithub.com/mattermost/mattermost/server/v8GHSA-m2w9-h2mm-79qr (opens in a new tab)
What to do
Solution: Update Mattermost to versions 11.7.0, 11.6.2, 11.5.5, 10.11.16, 10.11.17 or higher.
References
References1
- MMSA-2026-00656 (opens in a new tab)vendor-advisory
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-36499 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-m2w9-h2mm-79qr (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-6739)Record last updated .