What is CVE-2026-4646?

CVE-2026-4646 is a medium-severity vulnerability in Mattermost, classified under CWE-1287. CVSS score: 4.3/10. Published 2026-05-22.

How severe is CVE-2026-4646?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Vulnerability in Mattermost

CVE-2026-4646

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate user-supplied input in API request handlers which allows an authenticated attacker to crash the plugin process via a crafted HTT…

EPSS: 0.001 (21.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.

Affected products

Mattermost — versions 11.6.0, 11.5.0, 11.4.0
Mattermost Mattermost_server

Weakness classification (CWE)

CWE-1287

References

responsibledisclosure@mattermost.com (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2026-4646?: CVE-2026-4646 is a medium-severity vulnerability in Mattermost, classified under CWE-1287. CVSS score: 4.3/10. Published 2026-05-22.
How severe is CVE-2026-4646?: Medium severity. CVSS v3 base score is 4.3 out of 10.