A flaw was found in file-type, a library for detecting file types. A remote attacker can exploit this by providing a specially crafted ASF (Advanced Systems Format) file. When parsing the file, a zero-sized sub-header can trigger an infinite loop, leading to a Denial of Service (DoS). This can stall the Node.js event loop, preventing the application from processing further requests.

file-type detects the file type of a file, stream, or data. Prior to 21.3.1, 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. Fixed in version 21.3.1.

file-type affected by infinite loop in ASF parser on malformed input with zero-size sub-header