CVE-2026-19541
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 require re-entry of the stored client secret when validating an outgoing OAuth connection, which allows an authenticated user with permission to manage outgoing OAuth connections to obtain the secret via pointing the token URL at an attacker-controlled endpoint and triggering validation.. Mattermost Advisory ID: MMSA-2026-00761
SeverityMedium
CVSS6.5
Exploit probability—
Product
Mattermost Server
PublishedOct 16, 2026
First seenOct 16, 2026
Weakness typeCWE-201CWE-201
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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