Impact A denial of service vulnerability exists in the ASF (WMV/WMA) file type detection parser. When parsing a crafted input where an ASF sub-header has a size field of zero, the parser enters an infinite loop. The payload value becomes negative (-24), causing tokenizer.ignore(payload) to move the read position backwards, so the same sub-header is read repeatedly forever.

Any application that uses file-type to detect the type of untrusted/attacker-controlled input is affected. An attacker can stall the Node.js event loop with a 55-byte payload.

Patches Fixed in version 21.3.1. Users should upgrade to >= 21.3.1.

Workarounds Validate or limit the size of input buffers before passing them to file-type, or run file type detection in a worker thread with a timeout.

References - Fix commit: 319abf871b50ba2fa221b4a7050059f1ae096f4f

Reporter

crnkovic@lokvica.com