AirSane has a Remote Denial of Service (OOM) via Unvalidated Content-Length in HTTP Server

Summary

AirSane is a SANE frontend, and a scanner server that supports Apple's AirScan protocol. Versions prior to 0.4.12 have a vulnerability in the custom HTTP server implementation of AirSane that allows a remote unauthenticated attacker to cause a Denial of Service (DoS) via memory exhaustion (OOM). In httpserver.cpp, the HttpServer::Request::content function reads the Content-Length header and directly passes this value to std::string::resize() without any upper-bound validation or safe parsing. An attacker can send an HTTP POST request with an artificially large Content-Length value. This forces the daemon to attempt allocating gigabytes of memory, resulting in a std::bad_alloc exception and immediately crashing the AirSane process. Additionally, providing non-numeric characters in the Content-Length header leads to undefined behavior (NaN to integer conversion) due to the lack of error handling during header parsing. Version 0.4.12 patches the issue.