Debian LinuxOperating system · Debian
CVE-2017-5383
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 · uneditedURLs containing certain unicode glyphs for alternative hyphens and quotes do not properly trigger punycode display, allowing for domain name spoofing attacks in the location bar. This vulnerability affects Thunderbird < 45.7, Firefox ESR < 45.7, and Firefox < 51.
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 confidenceMozilla browsers fail to properly display punycode for URLs containing unicode glyphs that resemble standard hyphens and quotes, enabling attackers to spoof domain names in the location bar and trick users into believing they're on a legitimate website.
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
Debian LinuxOperating system
= 8.0
Enterprise LinuxOperating system
= 5.0= 6.0= 7.0
Enterprise Linux DesktopOperating system
= 5.0= 6.0= 7.0
Enterprise Linux ServerOperating system
= 5.0= 6.0= 7.0
Enterprise Linux Server AusOperating system
= 7.3= 7.4
Enterprise Linux Server EusOperating system
= 7.3= 7.4= 7.5
Enterprise Linux WorkstationOperating system
= 5.0= 6.0= 7.0
FirefoxWeb browser
< 51.0< 45.7.0CVSS 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
- 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 checksWork through these to decide whether this CVE applies to you.
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Check if Firefox is installedRun 'which firefox' or check your package manager for installed Firefox packages (e.g., 'rpm -qa | grep -i firefox' on RHEL, 'dpkg -l | grep -i firefox' on Debian)Affected if Firefox is not installed on the system
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Determine installed Firefox versionRun 'firefox --version' or check via package manager ('rpm -q firefox' on RHEL, 'dpkg -s firefox' on Debian)Affected if Command fails or returns no version information (Firefox may be installed but not accessible in PATH)
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Compare version against affected rangesFor standard Firefox: any version below 51.0 is affected. For ESR: any version below 45.7.0 is affected. Identify ESR by checking 'firefox --version' output for 'ESR' label or checking package name (e.g., firefox-esr)Affected if Firefox version is below 51.0 (standard) or below 45.7.0 (ESR)
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Verify browser is used on the systemCheck if Firefox is set as default browser or frequently used: look for desktop shortcuts, recent usage in ~/.local/share/applications, or check 'xdg-mime query default' for default browserAffected if Firefox is the primary or commonly used browser on this system
You are affected if Firefox (standard version below 51.0 or ESR version below 45.7.0) is installed and used as a browser on your Debian 8.0 or RHEL 5/6/7 system.
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 data45.7.051.0
Upgrade to Firefox 51+, Firefox ESR 45.7+, or Thunderbird 45.7+ to resolve the unicode/punycode handling issue.
Fix this in Debian Linux
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 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 $1,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-5383 — 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-2017-5383 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