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Cranelift CodegenApplication · Bytecodealliance

CVE-2022-31146

HIGH · 8.8 CVSS v3.1 Published 2022-07-21
Fix available
A fix is available. Upgrade to 0.38.2 / 0.85.2 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Wasmtime is a standalone runtime for WebAssembly. There is a bug in the Wasmtime's code generator, Cranelift, where functions using reference types may be incorrectly missing metadata required for runtime garbage collection. This means that if a GC happens at runtime then the GC pass will mistakenly think these functions do not have live references to GC'd values, reclaiming them and deallocating them. The function will then subsequently continue to use the values assuming they had not been GC'd, leading later to a use-after-free. This bug was introduced in the migration to the `regalloc2` register allocator that occurred in the Wasmtime 0.37.0 release on 2022-05-20. This bug has been patched and users should upgrade to Wasmtime version 0.38.2. Mitigations for this issue can be achieved by disabling the reference types proposal by passing `false` to `wasmtime::Config::wasm_reference_types` or downgrading to Wasmtime 0.36.0 or prior.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Wasmtime's Cranelift code generator has a bug where functions using WebAssembly reference types are missing metadata required for runtime garbage collection. When GC runs, it incorrectly thinks these functions have no live references to GC'd values, reclaiming them prematurely and causing a use-after-free. This bug was introduced in the migration to the regalloc2 register allocator in version 0.37.0.

MitigationUsers should upgrade to Wasmtime 0.38.2. Alternatively, disable the reference types proposal via `wasmtime::Config::wasm_reference_types(false)` or downgrade to version 0.36.0 or prior.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Cranelift CodegenApplication
Affected:>= 0.84.0, < 0.85.2
WasmtimeApplication
Affected:>= 0.37.0, < 0.38.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Wasmtime version
    Run `wasmtime --version` or inspect the Cargo.toml dependency version for wasmtime crate
    Affected if Version is >= 0.37.0 and < 0.38.2
  2. Check Cranelift Codegen version
    Inspect the Cargo.toml dependency version for cranelift-codegen crate if directly used
    Affected if Version is >= 0.84.0 and < 0.85.2
  3. Verify WebAssembly reference types are enabled
    Review the Wasmtime Config setup code for the call `config.wasm_reference_types(true)` or inspect if the default (enabled) is being used
    Affected if Reference types are explicitly enabled or defaults are used (they are enabled by default in affected versions)
  4. Identify if running WebAssembly modules using reference types
    Inspect the loaded WebAssembly modules for the presence of the reference types proposal (check module exports for any `ref.func`, `ref.extern`, `funcref`, or `externref` type usages)
    Affected if WebAssembly modules actively use reference types (funcref/externref) and the above version/config conditions are met

You are affected if you use Wasmtime 0.37.0-0.38.1 or Cranelift Codegen 0.84.0-0.85.1 with reference types enabled and execute WebAssembly modules that use funcref or externref types.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 0.38.2 / 0.85.2 or later
Fixed in 0.38.20.85.2
Interim mitigation

Users should upgrade to Wasmtime 0.38.2. Alternatively, disable the reference types proposal via `wasmtime::Config::wasm_reference_types(false)` or downgrade to version 0.36.0 or prior.

Recommended fix High confidence

Wasmtime 0.38.2 (or Cranelift 0.85.2)

  1. Upgrade Wasmtime to version 0.38.2 or later to receive the patched release that fixes the use-after-free vulnerability in Cranelift's reference types handling
  2. If using a package manager (e.g., Cargo), update the Wasmtime dependency in your Cargo.toml to specify version 0.38.2: wasmtime = "0.38.2"
  3. Run cargo update wasmtime to update the lockfile
  4. Rebuild and test your application to ensure compatibility with the new version
  5. Alternatively, if immediate upgrade is not possible, mitigate by disabling reference types: call config.wasm_reference_types(false) on your wasmtime::Config before creating the Engine
Caveat Review Wasmtime 0.38.0 and 0.38.1 release notes for any breaking changes between your current version and 0.38.2; general upgrade best practices apply

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Cranelift Codegen Scoped from the published advisory
  • Consultation3.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA3.0 h
24.0 hours of engineering $4,200
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2022-31146 in production — separate from our analysis above.

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What this is

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  • Version or environment caveats, and links to real fixes
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