CVE-2026-96259
MEDIUMCVSS 5.5Description
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
Timeline
Published:September 22nd, 2026 9:17 PM
Last modified:October 7th, 2026 4:41 PM
CVSS Scoring
CVSS v3: 5.5 (MEDIUM)
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
Affected Software
From NVD CPE configuration data
Vendors
mattermost
Products
mattermost_server
Weaknesses (CWE)
References & Reports
Advisories, patches, and third-party reports
Source: NIST NVD · Data may lag official sources by up to one minute