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FirefoxWeb browser · Mozilla

CVE-2024-9400

HIGH · 8.8 CVSS v3.1 Published 2024-10-01
Fix available
A fix is available. Upgrade to 128.3.0 / 131.0 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
A potential memory corruption vulnerability could be triggered if an attacker had the ability to trigger an OOM at a specific moment during JIT compilation. This vulnerability affects Firefox < 131, Firefox ESR < 128.3, Thunderbird < 128.3, and Thunderbird < 131.

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 · moderate confidence

A memory corruption vulnerability exists in Firefox and Thunderbird's JIT (Just-In-Time) compiler. An attacker who can trigger an out-of-memory condition at a specific moment during JIT compilation can cause memory corruption, potentially leading to arbitrary code execution.

MitigationUpdate affected products to Firefox 131+, Firefox ESR 128.3+, or Thunderbird 128.3+/131+ to patch this vulnerability.

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:< 128.3.0< 131.0
ThunderbirdApplication
Affected:< 128.3.0>= 129.0, < 131.0

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
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 the installed Mozilla product
    Check if Firefox or Thunderbird is installed by looking for the executable (firefox.exe on Windows, firefox on Linux) or checking installed programs. On Windows, look in Program Files folder; on Linux, check /usr/bin/firefox or /usr/bin/thunderbird.
    Affected if Either Firefox or Thunderbird is installed
  2. Determine the exact installed version
    For Firefox: Navigate to about:firefox in the address bar or use Help > About Firefox. For Thunderbird: Navigate to about:thunderbird or use Help > About Thunderbird. Record the full version number shown (e.g., 130.0.3).
    Affected if A version number is found that falls within the affected ranges: Firefox < 128.3.0 or < 131.0; Thunderbird < 128.3.0 or >= 129.0 but < 131.0
  3. Verify JIT compilation status
    In the address bar, type about:config and press Enter. Search for the javascript.options.jit property. If it exists, check its value - true means JIT is enabled.
    Affected if The javascript.options.jit preference is set to true (enabled). This is the default setting.
  4. Confirm browser is used to process untrusted content
    Review how the browser is used: if it regularly opens untrusted websites, runs extensions from unknown sources, or processes HTML email from unknown senders (for Thunderbird), the attack surface is higher.
    Affected if The user processes untrusted web content or email HTML/images through the browser, which can trigger JIT compilation paths.

You are affected if you are running Firefox or Thunderbird version below 128.3.0 or below 131.0 with JIT compilation enabled (the default), and you process untrusted content that could trigger the OOM timing condition during JIT compilation.

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 128.3.0 / 131.0 or later
Fixed in 128.3.0131.0
Interim mitigation

Update affected products to Firefox 131+, Firefox ESR 128.3+, or Thunderbird 128.3+/131+ to patch this vulnerability.

Recommended fix High confidence

Firefox 131.0 / Firefox ESR 128.3 / Thunderbird 128.3 (or 131.0)

  1. 1. Check current Firefox version by navigating to Menu > Help > About Firefox (or entering 'about:firefox' in address bar)
  2. 2. Check current Thunderbird version by navigating to Menu > Help > About Thunderbird
  3. 3. For Firefox: Download and install Firefox 131.0 or later from the official Mozilla website (www.mozilla.org)
  4. 4. For Firefox ESR: Download and install Firefox ESR 128.3 or later from the official Mozilla website
  5. 5. For Thunderbird: Download and install Thunderbird 128.3 or later (or 131.0+) from the official Mozilla website
  6. 6. Restart the application after installation
  7. 7. Verify the installed version matches or exceeds the fixed release (Firefox 131.0, Firefox ESR 128.3, Thunderbird 128.3 or 131.0)
Caveat Standard Mozilla release upgrades typically preserve user profiles and settings; minor UI changes may occur

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
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

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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-2024-9400 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