CVE Database

Starman versions before 0.4019 for Perl allow CPU exhaustion via quadratic regex backtracking when parsing chunked request bodies. Starman decodes chunked request bodies before calling the application, matching each chunk-size line with `s/^(([0-9a-fA-F]+).*\015\012)//`. A line of hex digits followed by a bare LF and then CRLF never matches, because `.` does not match LF, and each failed attempt backtracks in time quadratic in the length of the hex run. Nothing limits the length of the line. A remote attacker can exhaust worker CPU by sending such requests to any route.

Starman versions before 0.4019 for Perl allow a stalled request body to hold a worker indefinitely, as read_timeout covers only the headers. Content-Length and chunked request bodies are read with blocking reads and no deadline. A client that sends complete headers and then stalls or trickles the body keeps the worker waiting until it disconnects. A remote attacker can take every worker with a few such connections, five with the default worker count, so the server stops answering requests. Version 0.4019 applies read_timeout to each wait for body data and adds a body_timeout limit, 300 seconds by default, on the total time to read a body.