FirefoxWeb browser · Mozilla
CVE-2025-13019
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 · uneditedSame-origin policy bypass in the DOM: Workers component. This vulnerability was fixed in Firefox 145, Firefox ESR 140.5, Thunderbird 145, and Thunderbird 140.5.
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 same-origin policy bypass in the DOM: Workers component allows web content to circumvent origin-based restrictions, potentially enabling unauthorized cross-origin data access or actions. Web Workers normally execute in isolated contexts, but this vulnerability allowed those boundaries to be crossed.
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
< 140.5.0< 145.0CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/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 installed Firefox versionNavigate to Firefox menu > Help > About Firefox, or enter 'about:support' in the address bar. The version number is displayed at the top of the page.Affected if The displayed version is below 140.5.0 or falls between 141.0.0 and 144.x.x (any version < 145.0 that is not 140.5.0 or higher)
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Confirm browser is Firefox (not ESR or Thunderbird)In 'about:support', look at the 'Application Basics' section. The 'Application Name' field indicates whether you are running standard Firefox, Firefox ESR, or Thunderbird.Affected if The application is standard Firefox and the version falls into the affected ranges from step 1
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Check for Web Worker usage in your environmentReview any web applications or add-ons running in Firefox that utilize Web Workers. Inspect web application code for 'new Worker()' calls or examine browser console for Worker-related activity.Affected if Web Workers are actively used by content loaded in the browser, creating the attack surface for this vulnerability
You are affected if running Firefox versions below 140.5.0 or between 141.x and 144.x that load web content using Web Workers.
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 · scoped140.5.0145.0
Upgrade affected installations to Firefox 145+, Firefox ESR 140.5+, Thunderbird 145+, or Thunderbird 140.5+ to obtain the patched version of the Workers component.
Firefox 145 (or Firefox ESR 140.5)
- Check current Firefox version by navigating to about:support or Help > About Firefox
- Download Firefox 145 or later from the official Mozilla website (www.mozilla.org)
- Close all Firefox instances and run the installer
- For enterprise/ESR users, deploy Firefox ESR 140.5 or later via your management tools
- Restart Firefox and verify the update was applied
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 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 $1,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-13019 — 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-2025-13019 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