CVE-2026-4858: Mattermost has a Path Traversal issue

May 21, 2026 (updated June 23, 2026)

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.

References

github.com/advisories/GHSA-c4r7-j7pp-r8mp
mattermost.com/security-updates
nvd.nist.gov/vuln/detail/CVE-2026-4858

Code Behaviors & Features

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