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FirefoxWeb browser · Mozilla

CVE-2017-7763

MEDIUM · 5.3 CVSS v3.0 Published 2018-06-11
Fix available
A fix is available. Upgrade to 52.2.0 / 54.0 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 · unedited
Default fonts on OS X display some Tibetan characters as whitespace. When used in the addressbar as part of an IDN this can be used for domain name spoofing attacks. Note: This attack only affects OS X operating systems. Other operating systems are unaffected. This vulnerability affects Firefox < 54, Firefox ESR < 52.2, and Thunderbird < 52.2.

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 confidence

On OS X systems, certain Tibetan characters are rendered as whitespace by default fonts. When these characters appear in IDN (Internationalized Domain Names) displayed in the browser address bar, attackers can spoof legitimate domain names by mixing these invisible characters with visible ones, tricking users into believing they are visiting a genuine website.

MitigationUpgrade to Firefox 54 or later, Firefox ESR 52.2 or later, or Thunderbird 52.2 or later. This is a client-side browser vulnerability; no server-side changes are required.

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
Affected:< 52.2.0< 54.0
Debian LinuxOperating system
Affected:= 8.0= 9.0
ThunderbirdApplication
Affected:< 52.2.0

CVSS 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
Low
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Firefox version
    Run 'firefox --version' or look in Firefox menu > About Firefox. For ESR, check 'firefox-esr --version'
    Affected if Version is below 54.0 (regular) or below 52.2.0 (ESR)
  2. Check installed Thunderbird version
    Run 'thunderbird --version' or look in Thunderbird menu > About Thunderbird
    Affected if Version is below 52.2.0
  3. Confirm browser is running on Mac OS X or Debian Linux
    Run 'uname -a' or check system info. This vulnerability specifically affects these OS types
    Affected if OS is Mac OS X or Debian Linux 8.0/9.0 AND vulnerable Firefox/Thunderbird version is installed

User is affected if Firefox below 54.0 (or below 52.2.0 ESR) or Thunderbird below 52.2.0 is installed on Mac OS X or Debian Linux, allowing IDN spoofing via Tibetan characters.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to 52.2.0 / 54.0 or later
Fixed in 52.2.054.0
Interim mitigation

Upgrade to Firefox 54 or later, Firefox ESR 52.2 or later, or Thunderbird 52.2 or later. This is a client-side browser vulnerability; no server-side changes are required.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2017-7763 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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