CVE-2026-85684

marker through version 2.0.0 contains a path traversal flaw (CWE-73) in its FastAPI upload handler, where the client-supplied file.filename parameter is not sanitized. An unauthenticated attacker who can reach the /marker/upload endpoint can submit filenames containing directory traversal sequences, causing the server to write attacker-controlled files to arbitrary locations on the host or delete existing files. Because the CVSS 4.0 score of 8.8 assigns high impact to integrity and availability (with no confidentiality loss), the primary risk is file tampering, deletion, and potential follow-on compromise such as overwriting configuration or startup files. Any deployment running marker's FastAPI server at version 2.0.0 or earlier is affected, with the greatest risk on instances reachable by untrusted users or the internet. There is currently no known public proof of concept, the EPSS is 0.7% over 30 days (49th percentile), and the issue is not listed in CISA KEV, indicating no confirmed exploitation in the wild.

What to do: Upgrade marker to a release later than 2.0.0 as soon as a patched version is published (no fixed version is documented in the available data), and check the project's repository or vendor advisory for the fix. Until patched, restrict access to the /marker/upload endpoint using firewall rules, reverse-proxy allowlists, or network segmentation, and avoid exposing the service directly to the internet. Operators should also review hosts for unexpected new or missing files that could indicate exploitation.