CVE-2024-39274Malicious remote can add users to arbitrary teams and channels
- 8.7HighCVSS base score
- 0.34%Exploitation in 30 daysEPSS · top 72% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5 and 9.8.x <= 9.8.1 fail to properly validate that the channel that comes from the sync message is a shared channel, when shared channels are enabled, which allows a malicious remote to add users to arbitrary teams and channels
Timeline
ID reserved
By Mattermost
- 9 days later
· 9 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 | High8.7 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N |
| NVDNVD · Analyzed | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.34% · top 72% of all CVEs (13 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: High 8.7.
Affected products
- affected 9.9.0
- affected 9.5.0 – ≤ 9.5.6
- affected 9.7.0 – ≤ 9.7.5
- affected 9.8.0 – ≤ 9.8.1
- unaffected 9.10.0
- unaffected 9.9.1
- unaffected 9.5.7
- unaffected 9.7.6
- unaffected 9.8.2
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Gogithub.com/mattermost/mattermost/server/v8GHSA-cmc8-222c-vqp9 (opens in a new tab)
What to do
Solution: Update Mattermost to versions 9.10.0, 9.9.1, 9.5.7, 9.7.6, 9.8.2 or higher.
References
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-2024-2562 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-cmc8-222c-vqp9 (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-2024-39274)Record last updated .