Vulnerability in Mattermost
CVE-2026-4643
Mattermost Desktop App versions <=6.1 6.0.1 5.4.13.0 fail to prevent server-rendered content from closing an underlying application view in the Mattermost Desktop App which allows a malicious server or plugin to crash the desktop client via invoking {{window.close()}} in the renderer context, leading to a denial of service condition at the client level. Mattermost Advisory ID: MMSA-2026-00633
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.5 (Low). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.003 (19.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 19.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
- Mattermost — versions 0, 6.2.0, 6.1.1.0
- Mattermost Desktop
Weakness classification (CWE)
References
- mattermost.com/security-updates (vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-4643?
- CVE-2026-4643 is a low-severity vulnerability in Mattermost, classified under Improper Check for Unusual or Exceptional Conditions. CVSS score: 3.5/10. Published 2026-05-18.
- How severe is CVE-2026-4643?
- Low severity. CVSS v3 base score is 3.5 out of 10.