FirefoxWeb browser · Mozilla
CVE-2022-45407
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 · uneditedIf an attacker loaded a font using <code>FontFace()</code> on a background worker, a use-after-free could have occurred, leading to a potentially exploitable crash. This vulnerability affects Firefox < 107.
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 use-after-free vulnerability in Firefox occurs when the FontFace() API is used to load fonts on a background web worker. The browser incorrectly frees memory associated with the font object while it's still being referenced, allowing potentially exploitable memory corruption. This affects Firefox versions prior to 107.
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
< 107.0CVSS 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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Check installed Firefox versionOpen Firefox and navigate to Help > About Firefox, or enter 'about:support' in the address bar. Locate the 'Version' field.Affected if The version number displayed is less than 107 (e.g., 106.0, 105.0, etc.)
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Identify Web Worker usage in web applicationsReview web application source code, browser developer tools (Application > Service Workers), or network logs for references to 'new Worker()' or Web Worker script loading.Affected if Web Workers are actively used by applications running in the browser
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Detect FontFace() API usage on Web WorkersSearch web application code for 'FontFace' constructor calls within worker scripts, or use browser developer tools to inspect script execution context when fonts are loaded.Affected if Code contains FontFace() calls executing within Web Worker context (worker scripts that load fonts)
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Check for font loading behaviorOpen browser developer tools (F12), switch to the Console or Network tab, and observe if fonts are being loaded when Web Worker scripts execute.Affected if Fonts are loaded from within Web Worker scripts while using a vulnerable Firefox version
A user is affected if their Firefox version is below 107 AND they use web applications that invoke the FontFace() API to load fonts from within Web Worker contexts.
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 · scoped107.0
Upgrade Firefox to version 107 or later. Organizations should ensure browser update mechanisms are functioning and consider reviewing web applications that use FontFace() on Web Workers for potential exposure.
Firefox 107.0
- Upgrade Firefox to version 107.0 or later
- Verify the upgrade was successful by checking Help > About Firefox to confirm the version number
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 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-2022-45407 — 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-2022-45407 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
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