marker through 2.0.0 contains a path traversal vulnerability in the FastAPI /marker/upload handler that fails to sanitize the file.filename parameter. Unauthenticated attackers can supply filenames containing directory traversal sequences to write arbitrary files to any location or delete existing files on the system.

A path traversal vulnerability (CVE-2026-85684) exists in the marker application through version 2.0.0. The vulnerability resides in the FastAPI /marker/upload handler, which fails to sanitize the file.filename parameter. Unauthenticated attackers can exploit this flaw by supplying filenames containing directory traversal sequences (e.g., '../'). Successful exploitation allows attackers to write arbitrary files to any location on the system or delete existing files. The vulnerability requires no authentication, significantly lowering the barrier for exploitation. The affected code is located in marker/scripts/server.py. Users are advised to upgrade beyond version 2.0.0 or apply mitigations to sanitize uploaded filenames. The issue has been tracked and discussed in the marker GitHub repository issue #1047.