dbcve.org
FirefoxWeb browser · Mozilla

CVE-2024-3854

HIGH · 8.8 CVSS v3.1 Published 2024-04-16
Fix available
A fix is available. Upgrade to 115.10 / 125.0 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
In some code patterns the JIT incorrectly optimized switch statements and generated code with out-of-bounds-reads. This vulnerability affects Firefox < 125, Firefox ESR < 115.10, and Thunderbird < 115.10.

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

The JIT compiler in Mozilla's SpiderMonkey engine incorrectly optimizes switch statements, generating code that performs out-of-bounds memory reads. This arises from faulty optimization logic in the JIT's handling of switch jump tables, allowing reads beyond allocated array bounds.

MitigationUpgrade to Firefox 125, Firefox ESR 115.10, Thunderbird 115.10 or later to obtain the patched JIT compiler. No workarounds are available for earlier versions.

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:< 115.10< 125.0
ThunderbirdApplication
Affected:< 115.10

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 Firefox or Thunderbird version
    In Firefox, go to Menu > Help > About Firefox. In Thunderbird, go to Menu > Help > About Thunderbird. The version number is displayed in the window that opens.
    Affected if The version shown is lower than 115.10, OR it is between 115.10 and 124.x (inclusive)
  2. Verify the JIT compiler is enabled
    In the address bar, type about:config and press Enter. In the search box, type javascript.options.jit. Check if any JIT-related preference is set to true (such as javascript.options.jit.content or javascript.options.jit).
    Affected if Any JIT option is set to true - the vulnerability only exists when the JIT compiler is active
  3. Confirm you are using the baseline or optimizing JIT
    In the address bar, go to about:support. Look for the 'JavaScript' section. Check if 'Ion' or 'Baseline' JIT is listed as enabled, or look for the 'JIT Compiler' entry.
    Affected if The JIT compiler appears as enabled in the JavaScript support information
  4. Cross-reference your exact version against affected ranges
    For Firefox: if your version is below 115.10, you are affected. If it is 115.10 or higher but below 125.0, you are affected. For Thunderbird: if your version is below 115.10, you are affected.
    Affected if Your installed version falls into any of these ranges: Firefox < 115.10, Firefox 115.10 <= version < 125.0, or Thunderbird < 115.10

You are affected if your Firefox or Thunderbird version is below 115.10 (any edition) or between 115.10 and 124.x for Firefox, AND the JIT compiler is enabled in your browser settings.

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 115.10 / 125.0 or later
Fixed in 115.10125.0
Interim mitigation

Upgrade to Firefox 125, Firefox ESR 115.10, Thunderbird 115.10 or later to obtain the patched JIT compiler. No workarounds are available for earlier versions.

Recommended fix High confidence

Firefox 125.0 (or later), Firefox ESR 115.10 (or later), Thunderbird 115.10 (or later)

  1. Back up any important data from your Firefox/Thunderbird profile
  2. Update Firefox to version 125.0 or later (or Firefox ESR to 115.10 or later)
  3. Update Thunderbird to version 115.10 or later
  4. Restart the application after updating
  5. Verify the update by checking Help > About to confirm the installed version

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

Fix this in Firefox Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA8.0 h
40.0 hours of engineering $6,920
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $11,072.

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-2024-3854 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