CVE-2026-10542 Playbooks channel action update validation issue

Mattermost versions 11.9.x = 11.9.0, 11.8.x = 11.8.4, 11.7.x = 11.7.7, 10.11.x = 10.11.22 fail to validate channel action ownership which allows channel managers to update actions in other channels via the channel action update endpoint.. Mattermost Advisory ID: MMSA-2026-00692...

Mattermost Security Vulnerabilities

Mattermost is an open source collaboration platform from Mattermost, Inc. in the United States. A security vulnerability exists in Mattermost versions 8.1.x up to and including 8.1.9, which stems from an inability to clean data associated with permalinks. An attacker exploiting the vulnerability...