Deno is a JavaScript, TypeScript, and WebAssembly runtime. Starting in version 1.36.2 and prior to version 1.40.3, use of inherently unsafe const c_void and ExternalPointer leads to use-after-free access of the underlying structure, resulting in arbitrary code execution. Use of inherently unsafe const c_void and ExternalPointer leads to use-after-free access of the underlying structure, which is exploitable by an attacker controlling the code executed inside a Deno runtime to obtain arbitrary code execution on the host machine regardless of permissions.

This bug is known to be exploitable for both *const c_void and ExternalPointer implementations. Version 1.40.3 fixes this issue.