CVE-2026-4646
Medium
Description
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate user-supplied input in API request handlers which allows an authenticated attacker to crash the plugin process via a crafted HTTP request to the PR details endpoint.. Mattermost Advisory ID: MMSA-2026-00638
SeverityMedium
CVSS4.3
Exploit probability—
Product
Mattermost Server
PublishedMay 22, 2026
First seenMay 22, 2026
Weakness typeCWE-1287CWE-1287
How to fix
Update
- mattermost mattermost_server10.11.15, 11.4.5, 11.5.4, 11.6.1 or later
- github.com/mattermost/mattermost-server11.6.1, 11.5.4, 11.4.5, 10.11.15, 10.11.15+incompatible, 11.4.5+incompatible, 11.5.4+incompatible, 11.6.1+incompatible or later
- github.com/mattermost/mattermost-plugin-github1.0.1-0.20260330164815-c2840e980b3c or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mattermost mattermost_server | 10.11.0 ≤ v < 10.11.15, 11.4.0 ≤ v < 11.4.5, 11.5.0 ≤ v < 11.5.4, 11.6.0 ≤ v < 11.6.1 | 10.11.15, 11.4.5, 11.5.4, 11.6.1 |
| github.com/mattermost/mattermost-serverGo | 11.6.0 ≤ v < 11.6.1, 11.5.0 ≤ v < 11.5.4, 11.4.0 ≤ v < 11.4.5, 10.11.0 ≤ v < 10.11.15, 10.11.0+incompatible ≤ v < 10.11.15+incompatible, 11.4.0+incompatible ≤ v < 11.4.5+incompatible, 11.5.0+incompatible ≤ v < 11.5.4+incompatible, 11.6.0+incompatible ≤ v < 11.6.1+incompatible | 11.6.1, 11.5.4, 11.4.5, 10.11.15, 10.11.15+incompatible, 11.4.5+incompatible, 11.5.4+incompatible, 11.6.1+incompatible |
| github.com/mattermost/mattermost-plugin-githubGo | v < 1.0.1-0.20260330164815-c2840e980b3c | 1.0.1-0.20260330164815-c2840e980b3c |
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