FirefoxWeb browser · Mozilla
CVE-2025-11153
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 · uneditedJIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 143.0.3.
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 confidenceA miscompilation vulnerability exists in Firefox's JavaScript engine JIT (Just-In-Time) compiler. This flaw can produce incorrect optimized machine code during runtime, potentially leading to security bypasses or memory corruption. The issue was patched in Firefox version 143.0.3.
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
< 143.0.3CVSS 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
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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 checksWork through these to decide whether this CVE applies to you.
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Check Firefox version numberOpen Firefox, click the menu button (three horizontal lines), select Help, then About Firefox. The version number is displayed in the window that opens.Affected if The displayed version is earlier than 143.0.3 (for example, 143.0.2, 143.0.1, 142.x, etc.)
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Verify version via about:support pageType about:support in the Firefox address bar and press Enter. Look for the 'Version' field in the 'Application Basics' section.Affected if The version shown is less than 143.0.3
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Confirm JIT compiler is in useThe JavaScript JIT compiler is enabled by default in Firefox. This can be verified by typing about:config in the address bar, searching for 'javascript.options.jit.content', and confirming the value is set to true (this is the default state).Affected if The JIT compiler is enabled (default setting) AND the Firefox version is below 143.0.3
A user is affected if their Firefox installation is version 143.0.2 or earlier and the JavaScript JIT compiler remains in its default enabled state.
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 · scoped143.0.3
Organizations should ensure all Firefox installations are updated to version 143.0.3 or later to remediate this vulnerability.
Firefox 143.0.3
- Open Firefox and navigate to Help > About Firefox (or go to Settings > About Firefox on mobile)
- Allow Firefox to check for updates automatically
- If an update is available, download and install Firefox 143.0.3
- Restart Firefox to complete the update
- Alternatively, download Firefox 143.0.3 directly from the official Mozilla website (www.mozilla.org) and install it over your current version
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
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-11153 — 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-2025-11153 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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- 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
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