CVE-2026-18795Missing server side validation allowed user to quarantine a DM and GM post
- 6.4MediumCVSS base score
- 0.15%Exploitation in 30 daysEPSS · top 96% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to enforce DM/GM check on server side which allows an authenticated user to quarantine a post belonging to DM or GM via direct API call.. Mattermost Advisory ID: MMSA-2026-00756
Timeline
ID reserved
By Mattermost
- 2 months later
· 2 months 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 | Medium6.4 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L |
| NVDNVD · Analyzed | 3.1 | Medium6.4 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L |
- EPSS (exploitation in 30 days)
- 0.15% · top 96% 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 6.4.
Affected products
- affected 11.10.0 – ≤ 11.10.0
- affected 11.7.0 – ≤ 11.7.9
- affected 11.9.0 – ≤ 11.9.1
- affected 11.8.0 – ≤ 11.8.5
- unaffected 11.11.0
- unaffected 11.10.1
- unaffected 11.7.10
- unaffected 11.9.2
- unaffected 11.8.6
What to do
Solution: Update Mattermost to versions 11.11.0, 11.10.1, 11.7.10, 11.9.2, 11.8.6 or higher.
References
References1
- MMSA-2026-00756 (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-2026-102813 (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-2026-18795)Record last updated .