Bun v1.3.x baseline binary contains AVX2 instructions in the FFI/dlopen code path, crashing with SIGILL on AVX-only CPUs. Pin to pre-FFI versions as workaround.
Bun v1.3.x baseline builds crash with SIGILL (Illegal Instruction) when native modules are loaded via FFI on CPUs with AVX but not AVX2 (e.g., some AMD Ryzen PRO, virtualized guests with CPU masking). The crash occurs at a fixed address in Bun's dlopen bridging code.
Baseline builds explicitly claim to support CPUs with only SSE4.2/AVX and exclude AVX2. The FFI path containing AVX2 instructions violates this contract and is undocumented. The crash only manifests when native modules are actually invoked, making it a hidden incompatibility.
Bun's baseline build was compiled with code paths in the dynamic linking/FFI layer that use AVX2 SIMD despite the baseline constraint. The crash address is consistently 0x7FXXXE46690, indicating a static code path in the binary, not JIT-generated code. Disabling JIT tiers has no effect.
Pin to Bun versions or tool versions predating FFI integration. Upstream fix requires Bun to remove AVX2 instructions from baseline FFI bridge.
Any tool shipping Bun baseline as a dependency risks silent crashes on restricted/virtualized environments. Baseline build claim is broken for FFI-heavy workloads.