br_table is a WebAssembly instruction that selects a branch target from a list using an index value. It is commonly used to implement switch-like control flow. If the index is outside the listed targets, the instruction uses a designated default target.
Runtimes compile WebAssembly instructions such as br_table into native machine code, so correct handling is important to preserve the module’s control flow and sandbox boundaries. In an attack, a crafted module may exercise unusual or large branch tables to expose compiler errors; a flaw in translation could cause execution to behave outside the intended rules. Defenders should keep WebAssembly runtimes patched and restrict which untrusted modules they compile or run.