Vulnerability Details CVE-2026-96259
Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to apply the internal-connection filter to OAuth endpoint requests, which allows a System Administrator to make the server issue requests to internal network addresses and read the responses via the configured OAuth token and userinfo endpoints.. Mattermost Advisory ID: MMSA-2026-00776
Exploit prediction scoring system (EPSS) score
EPSS Score 0.003
EPSS Ranking 15.6%
CVSS Severity
CVSS v3 Score 5.5
References