CVE-2026-96259
Medium
Description
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
SeverityMedium
CVSS5.5
Exploit probability—
Product
Mattermost Server
PublishedSep 22, 2026
First seenSep 22, 2026
Weakness typeCWE-918Server-side request forgery (SSRF)
How to fix
Update
- mattermost mattermost_server11.7.11, 11.8.6, 11.9.2, 11.10.2 or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mattermost mattermost_server | 11.7.0 ≤ v < 11.7.11, 11.8.0 ≤ v < 11.8.6, 11.9.0 ≤ v < 11.9.2, 11.10.0 ≤ v < 11.10.2 | 11.7.11, 11.8.6, 11.9.2, 11.10.2 |
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