Rust and JavaScript Cross-Language Bugs Expose New Undefined Behavior Risks

Recent security incidents have highlighted that undefined behavior (UB) is no longer confined to C and C++, now affecting Rust and JavaScript ecosystems as well. Vulnerabilities in unsafe Rust code blocks, including a critical flaw in a Rust port of OpenSSL, allowed unchecked pointer arithmetic to compromise system safety at cross-language boundaries. In JavaScript, a Node.js zero-day exposed buffer over-read issues arising from mismatched memory lifetime assumptions between JavaScript's garbage collector and Rust's ownership model. Research also found that V8's JIT compiler could reorder operations in ways that enabled timing attacks against cryptographic libraries in browsers. Security experts warn that unsafe Rust blocks require the same rigorous auditing as C or C++ code, and that cross-language boundaries demand formal verification to prevent UB propagation.