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Low, CVSS 3.1

wasmtime vulnerable to miscompilation of i8x16.select with the same inputs on x86_64

CVE-2023-27477GHSA-xm67-587q-r2vw

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (cranelift-codegen 0.93.1, 0.92.1, 0.91.1; wasmtime 6.0.1, 5.0.1, 4.0.1), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • crates.io cranelift-codegen

    Affected
    >= 0.88.0, < 0.91.1>= 0.92.0, < 0.92.1>= 0.93.0, < 0.93.1
    Fixed in
    0.91.1, 0.92.1, 0.93.1

  • crates.io wasmtime

    Affected
    >= 1.0.0, < 4.0.1>= 5.0.0, < 5.0.1>= 6.0.0, < 6.0.1
    Fixed in
    5.0.1, 6.0.1, 4.0.1

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
3.1 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
EPSS
  • CVE-2023-27477: 0.62% estimated exploitation activity in the next 30 days; percentile 49.97 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Impact Wasmtime's code generation backend, Cranelift, has a bug on x8664 platforms for the WebAssembly i8x16.select instruction which will produce the wrong results when the same operand is provided to the instruction and some of the selected indices are greater than 16. There is an off-by-one error in the calculation of the mask to the pshufb instruction which causes incorrect results to be returned if lanes are selected from the second vector. The impact of this miscompilation is that the WebAssembly instruction can produce incorrect results for the i8x16.select instruction. This should have no effect on embedders and does not represent a sandbox escape, for example. Guest programs, however, may behave unexpectedly due to the incorrect result of this instruction. In extreme cases if a guest program is handling untrusted input then the guest program may deviate from its intended execution, for example calling an imported host function with different arguments than intended. This…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-xm67-587q-r2vw

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2023-27477

Advisory: wasmtime vulnerable to miscompilation of `i8x16.select` with the same inputs on x86_64
IDs: CVE-2023-27477, GHSA-xm67-587q-r2vw
Record: https://patchnext.com/advisories/cve-2023-27477 (revision 1, source checked 26 Oct 2026, 15:38 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: cranelift-codegen 0.93.1, 0.92.1, 0.91.1; wasmtime 6.0.1, 5.0.1, 4.0.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io cranelift-codegen: affected >= 0.88.0, < 0.91.1; >= 0.92.0, < 0.92.1; >= 0.93.0, < 0.93.1; fixed in 0.91.1, 0.92.1, 0.93.1
- crates.io wasmtime: affected >= 1.0.0, < 4.0.1; >= 5.0.0, < 5.0.1; >= 6.0.0, < 6.0.1; fixed in 5.0.1, 6.0.1, 4.0.1

## Suggested inspection (read-only)
- crates.io cranelift-codegen: check the installed version with your package manager.
- crates.io wasmtime: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on cranelift-codegen, wasmtime.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-xm67-587q-r2vw (GitHub-reviewed advisory GHSA-xm67-587q-r2vw lists affected ranges: crates.io wasmtime >=1.0.0 =5.0.0 =6.0.0 =0.88.0 =0.92.0 =0.93.0 <0.93.1)

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