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FirefoxWeb browser · Mozilla

CVE-2025-3031

MEDIUM · 6.5 CVSS v3.1 Published 2025-04-01
Fix available
A fix is available. Upgrade to 137.0 or later.
See remediation →
74/100
Remediation priority · Elevated
Remotely reachable No privileges 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
An attacker could read 32 bits of values spilled onto the stack in a JIT compiled function. This vulnerability was fixed in Firefox 137 and Thunderbird 137.

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

A vulnerability in Firefox and Thunderbird's JIT compiler allows an attacker to read 32 bits of values that were spilled onto the stack during JIT compilation. This is an information disclosure issue where stack-spilled values in JIT-compiled JavaScript functions can be accessed by an attacker.

MitigationUpdate Firefox and Thunderbird to version 137 or later to remediate this vulnerability. Organizations should ensure automatic updates are enabled or deploy the updated versions across managed endpoints.

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:< 137.0
ThunderbirdApplication
Affected:< 137.0

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
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

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

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 installed Firefox version
    Open Firefox, go to Menu > Help > About Firefox, or navigate to about:support in the address bar. The version number is displayed at the top of the page.
    Affected if The displayed version is less than 137.0 (e.g., 136.x, 135.x, etc.)
  2. Check installed Thunderbird version
    Open Thunderbird, go to Menu > Help > About Thunderbird, or navigate to about:support in the address bar. The version number is displayed at the top.
    Affected if Thunderbird is installed and the displayed version is less than 137.0 (e.g., 136.x, 135.x, etc.)
  3. Check Firefox version via command line
    Run 'firefox --version' or 'firefox -v' in a terminal/command prompt. On Windows, you can also check: 'C:\Program Files\Mozilla Firefox\firefox.exe -v'
    Affected if The reported version number is below 137.0
  4. Check Thunderbird version via command line
    Run 'thunderbird --version' or 'thunderbird -v' in a terminal/command prompt. On Windows, check: 'C:\Program Files\Mozilla Thunderbird\thunderbird.exe -v'
    Affected if The reported version number is below 137.0 (if Thunderbird is installed)

You are affected if any installed instance of Firefox or Thunderbird has a version number lower than 137.0.

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 137.0 or later
Fixed in 137.0
Interim mitigation

Update Firefox and Thunderbird to version 137 or later to remediate this vulnerability. Organizations should ensure automatic updates are enabled or deploy the updated versions across managed endpoints.

Recommended fix High confidence

Firefox 137.0 and Thunderbird 137.0

  1. Check current Firefox version by navigating to Help > About Firefox
  2. Check current Thunderbird version by navigating to Help > About Thunderbird
  3. Download Firefox 137.0 from the official Mozilla website (www.mozilla.org)
  4. Download Thunderbird 137.0 from the official Mozilla website (www.mozilla.org)
  5. Install the updated Firefox 137.0 installer
  6. Install the updated Thunderbird 137.0 installer
  7. Restart Firefox and Thunderbird after installation completes
  8. Verify the version by checking Help > About to confirm versions 137.0 or later are running
Caveat Standard minor version upgrade with no expected breaking changes; users should ensure system requirements are met

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

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.

Scan for this in your stack

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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-2025-3031 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