FirefoxWeb browser · Mozilla
CVE-2024-3858
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 · uneditedIt was possible to mutate a JavaScript object so that the JIT could crash while tracing it. This vulnerability affects Firefox < 125.
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 confidenceA vulnerability in Firefox's JavaScript JIT compiler allows attackers to crash the browser by mutating a JavaScript object during JIT tracing. This memory corruption issue in the SpiderMonkey engine could potentially be exploitable for arbitrary code execution.
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
< 125.0CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 checksWork through these to decide whether this CVE applies to you.
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Confirm Firefox installationLocate Firefox executable on the system. Common installation paths: Windows: C:\Program Files\Mozilla Firefox\firefox.exe, macOS: /Applications/Firefox.app, Linux: /usr/bin/firefox. Alternatively, search system for firefox binary.Affected if Firefox is present on the system
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Identify installed Firefox versionLaunch Firefox and navigate to Menu > Help > About Firefox, or type 'about:support' in the address bar to view the version number.Affected if Version number is displayed and can be recorded
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Compare against affected version rangeRecord the exact version number shown (for example: 124.0, 124.0.1, 124.3). Compare numerically: any version below 125.0 falls within the affected range.Affected if Installed version is less than 125.0 (for example: 124.x, 123.x, 122.x, etc.)
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Verify JavaScript JIT compiler statusIn Firefox address bar, enter 'about:config', accept the warning, then search for 'javascript.options.jit'. Check the value - true means JIT is enabled.Affected if javascript.options.jit is set to true (this is the default setting in Firefox)
System is affected if Firefox is installed with a version lower than 125.0 and JavaScript JIT compilation is enabled (default configuration).
Generated from the published advisory. Verify against your own configuration.
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 · scoped125.0
Update Firefox to version 125 or later. In enterprise environments, deploy the update via patch management and verify successful installation across affected systems.
Firefox 125.0
- Back up any important browser data (bookmarks, saved passwords, extensions) by exporting or using Firefox Sync
- Close all instances of Firefox
- Download Firefox 125.0 or later from the official Mozilla website (www.mozilla.org)
- Run the installer and follow the prompts to complete the upgrade
- Restart Firefox and verify the browser launches successfully
- Check that affected functionality works normally
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,456.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2024-3858 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2024-3858 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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