FirefoxWeb browser · Mozilla
CVE-2023-29540
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 · uneditedUsing a redirect embedded into <code>sourceMappingUrls</code> could allow for navigation to external protocol links in sandboxed iframes without <code>allow-top-navigation-to-custom-protocols</code>. This vulnerability affects Firefox for Android < 112, Firefox < 112, and Focus for Android < 112.
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 vulnerability in Firefox allows navigation to external protocol links (such as javascript: or data:) through redirects embedded in sourceMappingUrls within sandboxed iframes, bypassing the allow-top-navigation-to-custom-protocols security restriction.
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
< 112.0< 112.0CVSS 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
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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 versionOpen Firefox, click the menu button (three lines), select Help, then select About Firefox. Alternatively, type about:support in the address bar and look for the version number.Affected if The displayed version number is less than 112.0 (for example, 111.0, 110.0, etc.)
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Check Mozilla Focus versionOpen the Focus app, tap the menu or settings icon, scroll down and select Settings, then tap About Focus.Affected if The displayed version number is less than 112.0
If either Firefox or Mozilla Focus is installed at a version below 112.0, the browser is affected by this sandbox bypass vulnerability.
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 · scoped112.0
Upgrade Firefox, Firefox for Android, and Focus for Android to version 112 or later to patch this sandbox bypass vulnerability.
Firefox 112.0 / Focus for Android 112.0
- Open Firefox and navigate to Help > About Firefox to check the current version
- If the version is below 112.0, click 'Update to the latest version' or use the application's automatic update feature
- For Firefox for Android: Open Google Play Store, search for Firefox, and update to version 112.0 or later
- For Focus for Android: Open Google Play Store, search for Firefox Focus, and update to version 112.0 or later
- After updating, restart the browser application
- Verify the update was successful by checking the version again in Help > About Firefox
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 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-2023-29540 — 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-2023-29540 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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