Mattermost Path Traversal Vulnerability Allowing Thumbnail Overwrite in File Streaming APIs

A path traversal vulnerability has been identified in Mattermost versions 10.8.x prior to 10.8.3, 10.5.x prior to 10.5.8, 10.10.x prior to 10.10.0, and 10.9.x prior to 10.9.3. This vulnerability arises because the application fails to properly sanitize file names, enabling users with file upload permissions to overwrite file attachment thumbnails. The issue can be exploited through file streaming APIs by manipulating file paths.

Impact

Exploitation of this vulnerability allows for unauthorized overwriting of file attachment thumbnails, potentially leading to confusion or misrepresentation of file contents.

Remediation

Users can upgrade to Mattermost versions 10.11.0, 10.5.10, or 10.9.5 to address this vulnerability.