CVE-2026-1629: Operation on a Resource after Expiration or Release

Mattermost versions 10.11.x = 10.11.10 Fail to invalidate cached permalink preview data when a user loses channel access which allows the user to continue viewing private channel content via previously cached permalink previews until cache reset or relogin.. Mattermost Advisory ID: MMSA-2026-0058...

Mattermost Security Bypass Vulnerability

Mattermost is an open source collaboration platform from Mattermost, Inc. in the United States. A security bypass vulnerability exists in Mattermost that stems from an inability to check if the "Allow users to view archived channels" setting is enabled during the permalink preview display, even i...

CVE-2023-43754 Permalink previews displayed for posts in archived channels even if users are disallowed to view archived channels

Mattermost fails to check whether the “Allow users to view archived channels” setting is enabled during permalink previews display, allowing members to view permalink previews of archived channels even if the “Allow users to view archived channels” setting is disabled...