Security Vulnerability in WebAssembly's Sandbox Leading to Arbitrary Shell Execution on Host

The post discusses a security issue documented in WABT’s SECURITY.txt (issue #2831). WABT (WebAssembly Binary Toolkit) is a toolkit developed by WebAssembly.org (W3C), and its wasm2c tool is utilized by projects like Firefox (via RLBox) to compile WebAssembly into a sandboxed C library. A proof-of-concept (PoC) demonstrates that this sandbox can be escaped, undermining the assumption that the generated C code maintains WebAssembly’s security features, resulting in arbitrary shell execution on the host.