CVE-2026-12284
Mattermost Desktop App Missing IPC Sender Validation in Calls Leave Handler
- Published
- Updated
- Reserved
- Assigned by
- Mattermost
Description
Mattermost Desktop App versions <=6.2 6.2.2.0 fails to validate the IPC sender in the leaveCall handler which allows a malicious or compromised Mattermost server (or a user with script access to a connected server view) to disconnect an active call belonging to a different connected server via the desktopAPI.leaveCall IPC message. Mattermost Advisory ID: MMSA-2026-00699
Timeline
ID reserved
By Mattermost
- 3 months later
· 3 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 | Low3.8 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L |
| NVDNVD · Analyzed | 3.1 | Low3.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L |
- EPSS (exploitation in 30 days)
- 0.16% · top 94% of all CVEs (8 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: Low 3.8.
Weakness
Affected products
- affected ≤ 6.2.2
- unaffected 6.3.0
- unaffected 6.2.3.0
What to do
Solution: Update Mattermost Desktop App to versions 6.3.0, 6.2.3.0 or higher.
References (1)
- MMSA-2026-00699 (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)
- 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-2026-12284)Record last updated .