CVE-2026-6339 | Mattermost up to 11.4.3/11.5.1 Markdown origin validation

May 18, 2026 Yanac

A vulnerability was found in Mattermost up to 11.4.3/11.5.1. It has been classified as problematic. Affected by this issue is some unknown functionality of the component Markdown Handler. This manipulation causes origin validation error.

This vulnerability appears as CVE-2026-6339. The attack may be initiated remotely. There is no available exploit.

Upgrading the affected component is recommended.VulDB Recent EntriesRead More