Executive brief
WsgiDAV, a Python-based WebDAV server used for file sharing, contains a vulnerability that allows users to access files outside of their assigned folders. By sending specially crafted requests with encoded directory navigation characters, an attacker could read, modify, or delete sensitive files on the host system that they should not have access to. This risk is highest in environments where multiple folders are stored close together on the same server.
Technical details
A path traversal vulnerability exists in WsgiDAV's `FilesystemProvider._loc_to_file_path()` method. The component uses `os.path.abspath` to resolve paths but validates containment using a simple string prefix check (`startswith`) which is not path-boundary aware. An attacker can use encoded dot segments (e.g., `%2e%2e`) to resolve to a sibling directory that happens to share the same prefix as the intended root (e.g., `/tmp/share` vs `/tmp/share_evil`). If the WSGI layer passes these segments through and the process has sufficient OS permissions, the attacker can perform GET, PUT, and DELETE operations on files outside the restricted root. The issue is fixed in version 4.3.4.
Affected products
- mar10 WsgiDAV <= 4.3.3
Timeline
- 2026-05-27: disclosed
- 2026-06-11: advisory: GitHub Advisory published
- 2026-06-11: patched: Version 4.3.4 released