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FirefoxWeb browser · Mozilla

CVE-2022-31740

HIGH · 8.8 CVSS v3.1 Published 2022-12-22
Fix available
A fix is available. Upgrade to 91.10 / 101.0 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

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
On arm64, WASM code could have resulted in incorrect assembly generation leading to a register allocation problem, and a potentially exploitable crash. This vulnerability affects Thunderbird < 91.10, Firefox < 101, and Firefox ESR < 91.10.

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

On ARM64 architecture, Mozilla's JavaScript engine (SpiderMonkey) generates incorrect assembly code for WebAssembly, causing a register allocation bug that leads to a potentially exploitable memory safety crash.

MitigationUpgrade to Firefox 101+, Firefox ESR 91.10+, or Thunderbird 91.10+ to obtain the patched JavaScript engine with corrected WASM code generation for ARM64.

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
FirefoxWeb browser
Affected:< 101.0
Firefox EsrWeb browser
Affected:< 91.10
ThunderbirdApplication
Affected:< 91.10

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
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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. Identify your system architecture
    Run 'uname -m' or 'uname -a' on Linux/macOS, or check System Information on Windows to determine if the system is ARM64/aarch64. On Windows ARM, check the processor architecture in System Properties.
    Affected if The system is NOT ARM64/aarch64 - the vulnerability only affects ARM64 platforms, so x64/x86 systems are not impacted by this specific flaw.
  2. Confirm installed Firefox version
    In Firefox, navigate to 'Help' > 'About Firefox' or enter 'about:support' in the address bar. Note the version number displayed.
    Affected if The Firefox version is below 101.0 (for example, 100.x, 99.x, etc.) AND the system is ARM64.
  3. Confirm installed Firefox ESR version
    In Firefox ESR, navigate to 'Help' > 'About Firefox' or enter 'about:support' in the address bar. Note the version number displayed.
    Affected if The Firefox ESR version is below 91.10 AND the system is ARM64.
  4. Confirm installed Thunderbird version
    In Thunderbird, navigate to 'Help' > 'About Thunderbird' to display the version number.
    Affected if The Thunderbird version is below 91.10 AND the system is ARM64.

You are affected if you are running Firefox below 101.0, Firefox ESR below 91.10, or Thunderbird below 91.10 on an ARM64/aarch64 system, and you use WebAssembly functionality.

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 91.10 / 101.0 or later
Fixed in 91.10101.0
Interim mitigation

Upgrade to Firefox 101+, Firefox ESR 91.10+, or Thunderbird 91.10+ to obtain the patched JavaScript engine with corrected WASM code generation for ARM64.

Recommended fix High confidence

Firefox 101.0, Firefox ESR 91.10, Thunderbird 91.10

  1. Check current installed version of Firefox, Firefox ESR, or Thunderbird
  2. Download Firefox 101.0, Firefox ESR 91.10, or Thunderbird 91.10 from the official Mozilla website (www.mozilla.org)
  3. Close all instances of the affected application
  4. Install the downloaded update following standard installation procedures
  5. Restart the application and verify the version number reflects the update

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

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,808.

Scan for this in your stack

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dbcve dependency scanner

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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-2022-31740 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data