HTML::Entities versions before 3.84 for Perl read freed heap memory in decodeentities

WWW::Mechanize::Cached versions before 2.00 for Perl deserialize cached HTTP responses from a world-writable on-disk cache, enabling local response forgery and code execution.

With no explicit cache backend, WWW::Mechanize::Cached constructs a default Cache::FileCache under /tmp/FileCache without overriding the backend's documented directoryumask of 000, so the cache root and its subdirectories are created mode 0777 with no sticky bit. Cache entries are named by sha1hex of the request and read back through Storable::thaw on the next cache hit.

A local attacker with write access to the cache tree can replace a victim's cache entry for a known URL with an arbitrary frozen HTTP::Response blob, causing the victim's next get() of that URL to return attacker controlled response bytes. Because the bytes are passed to Storable::thaw, a victim process that has loaded any class with a side-effectful STORABLEthaw, DESTROY, or overload hook can be escalated to arbitrary code execution.