What is CVE-2026-10103?

CVE-2026-10103 is a medium-severity vulnerability in Mattermost, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2026-07-13.

How severe is CVE-2026-10103?

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

Auth bypass in Mattermost

CVE-2026-10103

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to verify post ownership in the shared channel inbound sync handler, which allows an authenticated remote cluster to modify or delete posts authored by local…

Vulnerability class: IDOR (Insecure Direct Object Reference)

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:L/A:N.

Affected products

Mattermost — versions 11.7.0, 11.6.0, 10.11.0
Mattermost Mattermost_server

Weakness classification (CWE)

CWE-639 — Authorization Bypass Through User-Controlled Key

References

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

Frequently asked questions

What is CVE-2026-10103?: CVE-2026-10103 is a medium-severity vulnerability in Mattermost, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2026-07-13.
How severe is CVE-2026-10103?: Medium severity. CVSS v3 base score is 4.3 out of 10.