medium6.7
CVE-2026-6739
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 protecte…
Impact
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
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/mattermost/mattermost-server | = 11.6.0 | 11.6.1 |
| go | github.com/mattermost/mattermost/server/v8 | >= 8.0.0-20250731163400-5b955468ea1e, < 8.0.0-20260501142004-99b73d4c4acf | 8.0.0-20260501142004-99b73d4c4acf |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Mattermost | Mattermost Server | from 10.11.0 before 10.11.17 from 11.5.0 before 11.5.5 from 11.6.0 before 11.6.2 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-m2w9-h2mm-79qr
- https://nvd.nist.gov/vuln/detail/CVE-2026-6739
- https://mattermost.com/security-updates
- https://github.com/mattermost/mattermost/pull/36197
- https://github.com/mattermost/mattermost/pull/36377
- https://github.com/mattermost/mattermost/pull/36379
- https://github.com/mattermost/mattermost/pull/36380
- https://github.com/mattermost/mattermost/pull/36382
- https://github.com/mattermost/mattermost/commit/2c89c2f6768fbe4dfd57a21ca38c0aecead8d4a8
- https://github.com/mattermost/mattermost/commit/5e159647b16e571b327ac6882f32eae42971f540
- https://github.com/mattermost/mattermost/commit/8000e5933526f4fd66b92131db3a1b1f4520dbae
- https://github.com/mattermost/mattermost/commit/f0a390b96e4c730daedbaf5190684776730218c7
- 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