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CVE-2026-115889

Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompilation PUBLISHED

Description (CNA)

Wasmtime is a runtime for WebAssembly. Prior to 36.0.19 and 43.0.0, the Cranelift compiler backend bit-packs SSA value indices in a way that can silently overflow in release builds when compiling a sufficiently large or specially crafted Wasm function with many SSA values. The overflow can make Cranelift reference incorrect IR values, causing arbitrary miscompilation, type confusion, and other attacker-controlled effects that may escape the Wasm sandbox on any architecture using the default Cranelift backend. This issue is fixed in versions 36.0.19 and 43.0.0.

Affected (CNA)

Vendor / productVersions
bytecodealliance / wasmtimeaffected < 36.0.19; affected >= 37.0.0, < 43.0.0

CWE

CWE-197, CWE-843

References