CVE-2026-96259 — Mattermost server-side request forgery via OAuth endpoints configurable by a System Administrator
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 allo…
Published: 2026-09-22 · CVSS: 5.5 · CVSS 3.1
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
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7