FirefoxWeb browser · Mozilla
CVE-2018-5132
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 Find API for WebExtensions can search some privileged pages, such as "about:debugging", if these pages are open in a tab. This could allow a malicious WebExtension to search for otherwise protected data if a user has it open. This vulnerability affects Firefox < 59.
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 confidenceThe WebExtensions Find API in Firefox versions prior to 59 incorrectly allowed searching privileged 'about:' pages (such as about:debugging) that contain sensitive internal Firefox information. A malicious extension could exploit this to extract protected data from these privileged pages when open in a tab.
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
< 59.0
Ubuntu LinuxOperating system
= 14.04= 16.04= 17.10CVSS 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
- High
- Integrity
- None
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/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 installed Firefox versionRun 'firefox --version' or 'firefox -v' in terminal, or click Menu > Help > About FirefoxAffected if The displayed version is below 59.0 (e.g., 58.x, 57.x, etc.)
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Check Firefox package version on UbuntuRun 'dpkg -l | grep firefox' or 'apt policy firefox' in terminalAffected if The installed firefox package version is less than 59.0 (for Ubuntu 14.04, 16.04, or 17.10 the packaged Firefox is vulnerable)
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Verify if WebExtensions are enabledIn Firefox, navigate to 'about:addons' and click 'Extensions' in the left panel. Check if any extensions are installedAffected if Any WebExtensions are installed and enabled - the vulnerability requires a malicious extension to exploit it (the presence of extensions increases risk, though not all are malicious)
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Check for privileged about: pagesInspect open tabs in Firefox for URLs starting with 'about:' such as about:debugging, about:config, or about:addonsAffected if Any privileged about: pages are currently open in tabs - these contain sensitive internal Firefox information that could be extracted if a malicious extension attempts exploitation
You are affected if Firefox version is below 59.0 AND you have WebExtensions installed with privileged about: pages potentially open in tabs.
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 data59.0
Update Firefox to version 59 or later to patch the Find API restriction bypass. Additionally, review and audit installed WebExtensions for suspicious behavior.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 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 $1,456.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-5132 — 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-2018-5132 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
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