Firefox MobileWeb browser · Mozilla
CVE-2021-29993
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 · uneditedFirefox for Android allowed navigations through the `intent://` protocol, which could be used to cause crashes and UI spoofs. *This bug only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 92.
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 confidenceFirefox for Android versions prior to 92 contained a flaw in handling the `intent://` protocol that allowed arbitrary navigations. This could be exploited to cause application crashes or perform UI spoofing attacks, tricking users into interacting with malicious content masquerading as legitimate interfaces.
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
Firefox MobileWeb browser
< 92.0CVSS 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
- None
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/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 checksWork through these to decide whether this CVE applies to you.
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Confirm the product is Firefox for AndroidCheck the installed application name and package identifier. On Android, go to Settings > Apps > Mozilla Firefox. The package name should be 'org.mozilla.firefox'.Affected if The installed browser is NOT Firefox for Android (e.g., Firefox for desktop, Firefox Focus, or another browser)
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Check the installed Firefox for Android versionOpen Firefox for Android, tap the three-dot menu, go to Settings > About Firefox. The version number is displayed there.Affected if The displayed version number is less than 92 (for example, 91.x or earlier)
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Verify intent:// protocol handling is activeThe vulnerability affects any use of the intent:// protocol within Firefox for Android. This protocol is commonly used for deep linking in Android apps. Test by loading any webpage containing intent:// links, or check browser history for any recent intent:// navigations.Affected if Intent:// protocol handling is enabled and the browser version is below 92
A user is affected if they are running Firefox for Android with a version number lower than 92 and the intent:// protocol feature is active in their browser.
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 · scoped92.0
Upgrade Firefox for Android to version 92 or later. Users should be advised to update their mobile browser through the Google Play Store or enterprise mobile management tooling.
Firefox 92.0 for Android
- 1. Open the Google Play Store app on your Android device
- 2. Search for "Firefox" or "Mozilla Firefox"
- 3. Tap on Firefox for Android
- 4. Tap the "Update" button if an update is available
- 5. Ensure the updated version is 92.0 or higher
- 6. Alternatively, enable automatic updates in the Play Store to receive future security patches automatically
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox Mobile
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-2021-29993 — 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-2021-29993 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