- 4.9MediumCVSS base score
- 0.36%Exploitation in 30 daysEPSS · top 70% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate that an assigned incoming webhook user has access to the target team or channel, which allows a requester with webhook management permissions to create posts or direct messages attributed to another user via crafted incoming webhook configuration and payloads.. Mattermost Advisory ID: MMSA-2026-00683
Timeline
ID reserved
By Mattermost
- 47 days later
· 47 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 | Medium4.9 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N |
| NVDNVD · Analyzed | 3.1 | Medium4.9 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.36% · top 70% of all CVEs (11 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 4.9.
Affected products
- affected 11.7.0 – ≤ 11.7.2
- affected 11.6.0 – ≤ 11.6.4
- affected 10.11.0 – ≤ 10.11.19
- unaffected 11.8.0
- unaffected 11.7.3
- unaffected 11.6.5
- unaffected 10.11.20
What to do
Solution: Update Mattermost to versions 11.8.0, 11.7.3, 11.6.5, 10.11.20 or higher.
References
References1
- MMSA-2026-00683 (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-2026-43308 (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-2026-9708)Record last updated .