CVE-2026-15754Missing per-channel team-scope check in ABAC access control policy unassign allows cross-team policy removal
- 4.2MediumCVSS base score
- 0.25%Exploitation in 30 daysEPSS · top 84% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
Mattermost versions 11.7.x <= 11.7.6, 11.8.x <= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718
Timeline
ID reserved
By Mattermost
- 34 days later
· 34 days later
Published
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 | Medium4.2 | CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N |
| NVDNVD · Analyzed | 3.1 | Medium4.2 | CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.25% · top 84% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.2.
Affected products
- affected 11.7.0 – ≤ 11.7.6
- affected 11.8.0 – ≤ 11.8.3
- unaffected 11.9.0
- unaffected 11.7.7
- unaffected 11.8.4
What to do
Solution: Update Mattermost to versions 11.9.0, 11.7.7, 11.8.4 or higher.
References
References1
- MMSA-2026-00718 (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-2026-60212 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (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-2026-15754)Record last updated .