Seerr is an open-source media request and discovery manager for Jellyfin, Plex, and Emby. Prior to version 3.4.0, Seerr's ImageProxy in server/lib/imageproxy.ts uses the upstream ETag and Content-Type response headers to build a cache filename for the unauthenticated GET /avatarproxy/:jellyfinUserId route, allowing a malicious or compromised Jellyfin or Emby server, or a man-in-the-middle attacker on a plaintext media-server connection, to supply traversal sequences that path.join and fs.writeFile normalize outside the cache directory, overwrite /app/dist/index.js or other files, and execute code as the node user after a container restart. This issue is fixed in version 3.4.0.
Attack Parameters
Attack Vector
Adjacent
Requires local network access
Attack Complexity
High
Difficult to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
References 3
https://github.com/seerr-team/seerr/commit/f484791105bd81bd5404e01410431ee6fe57…
security-advisories@github.com
https://github.com/seerr-team/seerr/releases/tag/v3.4.0
security-advisories@github.com
https://github.com/seerr-team/seerr/security/advisories/GHSA-mc6w-69r3-62h8
security-advisories@github.com