CVE-2026-96259CWE-918ssrf

CVE-2026-96259

Medium · published September 23, 2026

CVSS v3.1
5.5
EPSS
0%
Percentile
16.1
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
5.5 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00255 · 16.1th percentile
Weakness
CWE-918 · Server-Side Request Forgery (SSRF)
Published
2026-09-23T01:17Z
Affected products (4)
ProductVersionsFixed in
mattermost/mattermost_server≥ 11.7.0, < 11.7.1111.7.11
mattermost/mattermost_server≥ 11.8.0, < 11.8.611.8.6
mattermost/mattermost_server≥ 11.9.0, < 11.9.211.9.2
mattermost/mattermost_server≥ 11.10.0, < 11.10.211.10.2
References (1)
https://mattermost.com/security-updates · [email protected]
EPSS history
Timeline
  • 24 SEP 03:25Z
    EPSS moved — → 0%
    epss
  • 22 SEP 20:34Z
    Mattermost server-side request forgery via OAuth endpoints configurable by a System Administrator
    cvelistv5