[BUG] /sandbox reports as unsupported in Linux when run under WSL2

Found 1 possible duplicate issue:

1. https://github.com/anthropics/claude-code/issues/10038

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🤖 Generated with Claude Code

I can confirm that the bug is present even after running sudo apt install bubblewrap in WSL (as bubblewrap is documented as being the underlying mechanism for sandboxing).

From Claude Code itself:

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Technical Analysis of WSL2 Sandbox Detection Issue

I've done some reverse engineering of the Claude Code binary to understand why sandboxing is rejected on WSL2 despite it being functionally equivalent to native Linux.

Investigation Findings

Platform Detection Logic (from cli.js):

F0Q(A){return["macos","linux"].includes(A)}

The code checks if the platform is in the allowed list ["macos","linux"], and for Linux specifically, it verifies that bwrap and socat are available.

System Status on WSL2:

$ node -e "console.log(process.platform)"
linux  ✓

$ uname -a
Linux LAPTOP-Q5I0LUG8 6.6.87.2-microsoft-standard-WSL2 ...

$ which bwrap && which socat
/usr/bin/bwrap  ✓
/usr/bin/socat  ✓

All prerequisites are met:

• ✅ process.platform returns "linux"
• ✅ bwrap is installed and available
• ✅ socat is installed and available

Root Cause:

Despite Node.js correctly identifying WSL2 as Linux (process.platform === "linux"), Claude Code appears to have an additional check that explicitly rejects WSL environments. This is likely done by:

1. Checking /proc/version for "microsoft" or "WSL" strings, OR
2. Examining os.release() which returns "6.6.87.2-microsoft-standard-WSL2", OR
3. Some other WSL-specific detection mechanism

The platform detection function HB() must be returning something other than "linux" when it detects WSL, causing the F0Q() check to fail.

Conclusion:

This appears to be an intentional but overly restrictive check. WSL2 is a legitimate Linux environment with full system call compatibility, and the required sandboxing tools (bwrap, socat) work correctly on it.

Recommendation: Relax the platform check to allow WSL2, or at minimum provide a way for users to override this restriction with an environment variable or config flag.

This might be because of :

/tmp node -p "require('os').release()"
5.15.167.4-microsoft-standard-WSL2

Claude code looks at that kernel release string, sees "microsoft" or "WSL", and throws the error?
It would be great to fix as WSL2 is microVM and bubblewrap should work on it without issues

Are there any updates regarding this? It seems to be a pretty large security hole for a large community of users.

I asked Claude Code to patch out it's own WSL2 check, and it seems to work. The first attempt was pretty heavy-handed, but the second try was more surgical and swapped out Microsoft -> Micros0ft and wsl -> ws1 in 10 locations.

Perhaps not a _good_ idea, but...might be fine until we get an official patch. 🤷

I'm having the same issue, can't use sandbox on wsl2😵

Getting this issue too. Any news?

Also having this issue - would really appreciate a permanent fix:)

I'm also facing the same issue on OS release 5.15.167.4-microsoft-standard-WSL2. Any news on the same?

+1

+1

Editing the binary works just fine:

with open("claude", "rb") as fin:
    cl = fin.read().replace(b'includes("wsl")', b'includes("wfl")').replace(b'includes("microsoft")', b'includes("marcosaft")')

with open("claude-cleaned", "wb") as fout:
    fout.write(cl)

After that the sandbox is fine. No warranty on the quality of the sandbox. Maybe there is a good reason it is turned off on wsl2.

For whatever reason using LD_PRELOAD to hide the strings WSL and Microsoft from uname() does not fix it.

After that the sandbox is fine. No warranty on the quality of the sandbox. Maybe there is a good reason it is turned off on wsl2.

The official docs claim WSL2 support via bubblewrap. https://code.claude.com/docs/en/sandboxing#os-level-enforcement

* WSL2: Uses bubblewrap, same as Linux WSL1 is not supported because bubblewrap requires kernel features only available in WSL2.

This is a recent fix. The latest binaries work with wsl2 out of the box.

Claude Code 2.1.71 on WSL2
bwrap and socat verified installed
settings.json correctly configured at ~/.claude/settings.json with both enabled: true and mode: auto-allow
/sandbox menu shows dependencies installed but no Mode/Overrides options
/config shows no sandbox entry at all
--sandbox CLI flag doesn't exist
Settings file is being read (correct Linux $HOME, correct ownership) but sandbox key is silently ignored