FirefoxWeb browser · Mozilla
CVE-2013-1699
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 · uneditedThe Internationalized Domain Name (IDN) display algorithm in Mozilla Firefox before 22.0 does not properly handle the .com, .name, and .net top-level domains, which allows remote attackers to spoof the address bar via unspecified homograph characters.
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 before 22.0 contains a flaw in its Internationalized Domain Name (IDN) display algorithm for .com, .name, and .net TLDs. The algorithm fails to properly handle homograph characters - visually similar characters from different scripts (e.g., Cyrillic vs Latin) that can appear identical in the address bar. This allows attackers to register domains that visually spoof legitimate sites, enabling phishing attacks.
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
<= 21.0= 19.0= 19.0.1= 19.0.2= 20.0= 20.0.1CVSS 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
- Authentication
- None
- Confidentiality
- None
- Integrity
- Partial
- Availability
- None
AV:N/AC:L/Au:N/C:N/I:P/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.
-
Check Firefox version numberOpen Firefox, click the menu button (three horizontal lines), select Help, then About Firefox. The version number is displayed on the page that opens.Affected if The version is 21.0 or earlier, or specifically 19.0, 19.0.1, 19.0.2, 20.0, or 20.0.1.
-
Verify IDN support is enabledType about:config in the address bar, press Enter, accept the warning. Search for the setting network.IDN.enable. Check if the value is set to true.Affected if network.IDN.enable is set to true and the Firefox version is in the affected list.
-
Confirm TLD in useThe vulnerability affects .com, .name, and .net TLDs specifically. Inspect the domain being visited in the address bar.Affected if The browser is displaying a domain in one of these TLDs that contains non-ASCII characters visually similar to ASCII characters.
You are affected if Firefox version is 21.0 or earlier (specifically 19.x or 20.x) and network.IDN.enable is set to true while viewing IDN domains in .com, .name, or .net TLDs.
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.
From vendor dataUpdate Firefox to version 22.0 or later, which contains the corrected IDN display algorithm. Alternatively, consider disabling IDN display in the browser or implementing additional browser-side protections against homograph attacks.
Fix this in Firefox
Scoped from the published advisory
- Consultation3.0 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 $2,880.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2013-1699 — 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-2013-1699 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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