Bun 1.3.14 crashes with Illegal instruction on Intel i5-2540M / Windows 11

[MahmoudHooda2019]

Description

Freebuff Desktop fails to start its orchestrator because the bundled Bun runtime crashes immediately with an Illegal instruction.

The application bundles:

Bun v1.3.14 (0d9b296a)
Windows x64

The crash occurs before orchestrator.js can run.

Environment

• OS: Windows 11 x64

• CPU: Intel(R) Core(TM) i5-2540M CPU @ 2.60GHz

• CPU vendor: GenuineIntel

• Bun: 1.3.14 (0d9b296a)

• Freebuff bundled runtime:

  C:\Users\Admin\AppData\Local\Programs\@codebufffreebuff-desktop\resources\bun\bun.exe
  

• Bun reports:

  CPU: sse42 avx
  Features: no_avx2
  

Steps to reproduce

Run the bundled Bun executable directly from PowerShell:

& "C:\Users\Admin\AppData\Local\Programs\@codebufffreebuff-desktop\resources\bun\bun.exe" --version

The command does not return normally. Bun prints its runtime information and then crashes:

Bun v1.3.14 (0d9b296a) Windows x64
Windows v.win11_dt
CPU: sse42 avx
Args:
Features: no_avx2

panic: Illegal instruction at address 0x7FF75D64F82C
panicked during a panic. Aborting.

Freebuff consequently fails when attempting to launch:

resources\orchestrator\orchestrator.js

Important observation

This failure happens when executing:

bun.exe --version

Therefore, the problem does not appear to originate from orchestrator.js or the application JavaScript code.

The failure occurs directly inside the bundled Bun executable.

The CPU supports AVX but does not support AVX2, and Bun explicitly reports:

Features: no_avx2

Expected behavior

The bundled runtime should start successfully on supported non-AVX2 x64 CPUs, or the application should provide/use a compatible baseline Bun binary.

At minimum, Freebuff should detect an incompatible CPU/runtime combination and provide a clear error instead of crashing with an Illegal instruction.

Actual behavior

Bun 1.3.14 terminates with:

panic: Illegal instruction
panicked during a panic. Aborting.

This prevents Freebuff Desktop from launching its orchestrator.

Possible cause

The bundled Bun 1.3.14 binary may contain CPU instructions that require AVX2 despite reporting:

Features: no_avx2

A CPU-compatible Windows x64 baseline build, or a Bun version compatible with non-AVX2 processors, may be required.

Requested fix

Please consider one of the following:

1. Ship the appropriate Windows x64 baseline Bun binary for CPUs without AVX2.
2. Use a Bun version that supports this CPU class.
3. Detect CPU capabilities before launching Bun and provide a meaningful compatibility error.
4. Consider allowing the bundled runtime to be replaced/configured when running on older CPUs.

Additional information

The CPU is:

Intel(R) Core(TM) i5-2540M CPU @ 2.60GHz

Bun itself identifies the CPU capabilities as:

CPU: sse42 avx
Features: no_avx2

The crash is reproducible every time when running the bundled bun.exe --version.

Full error

[2026-08-12T12:53:38.038Z] Starting Freebuff orchestrator
Runtime: C:\Users\Admin\AppData\Local\Programs\@codebufffreebuff-desktop\resources\bun\bun.exe
Arguments: C:\Users\Admin\AppData\Local\Programs\@codebufffreebuff-desktop\resources\orchestrator\orchestrator.js

============================================================
Bun v1.3.14 (0d9b296a) Windows x64
Windows v.win11_dt
CPU: sse42 avx
Args:
Features: no_avx2

panic: Illegal instruction at address 0x7FF622C0F82C
panicked during a panic. Aborting.