CVE-2026-4858
High
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 check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action URL.. Mattermost Advisory ID: MMSA-2026-00640
SeverityHigh
CVSS8.0
Exploit probability26. percentile0.3%
Product
Mattermost Server
PublishedMay 21, 2026
First seenMay 21, 2026
Weakness typeCWE-22Path traversal
How to fix
Update
- mattermost mattermost_server10.11.15, 11.4.5, 11.5.4 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
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 | 10.11.15, 11.4.5, 11.5.4 |
| 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 |
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