What is CVE-2026-10080?

CVE-2026-10080 is a medium-severity vulnerability in Mattermost, classified under Incorrect Type Conversion or Cast. CVSS score: 6.5/10. Published 2026-08-17.

How severe is CVE-2026-10080?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Mattermost

CVE-2026-10080

Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to validate WebSocket command field types which allows an authenticated user to crash the plugin process and deny service to all Boards users via a custom_focalboard_SUBSCRIBE_TEAM message with a non-string teamId.. Mattermost Advisory ID: MMSA-2026-00687

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Affected products

Mattermost — versions 11.7.0, 10.11.0, 11.8.0

Weakness classification (CWE)

CWE-704 — Incorrect Type Conversion or Cast

References

responsibledisclosure@mattermost.com (vendor-advisory)

Frequently asked questions

What is CVE-2026-10080?: CVE-2026-10080 is a medium-severity vulnerability in Mattermost, classified under Incorrect Type Conversion or Cast. CVSS score: 6.5/10. Published 2026-08-17.
How severe is CVE-2026-10080?: Medium severity. CVSS v3 base score is 6.5 out of 10.