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FirefoxWeb browser · Mozilla

CVE-2018-12369

CRITICAL · 9.8 CVSS v3.0 Published 2018-10-18
Fix available
A fix is available. Upgrade to 60.1.0 / 61.0 or later.
See remediation →
100/100
Remediation priority · Urgent
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
WebExtensions bundled with embedded experiments were not correctly checked for proper authorization. This allowed a malicious WebExtension to gain full browser permissions. This vulnerability affects Firefox ESR < 60.1 and Firefox < 61.

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

Firefox WebExtensions with embedded experiments had a missing/incorrect authorization check that allowed malicious extensions to bypass permission validation and gain full browser privileges. This is a privilege escalation vulnerability in the extension loading mechanism.

MitigationUpdate Firefox to version 61 or Firefox ESR to 60.1 or later to obtain the patched version. Review installed extensions for suspicious behavior.

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:< 60.1.0< 61.0
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 17.10= 18.04

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
High
Integrity
High
Availability
High

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

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

  1. Determine installed Firefox version
    Open Firefox, click the menu button (three horizontal lines), select Help, then About Firefox. Alternatively, navigate to about:support in the address bar or run 'firefox --version' from command line.
    Affected if Version is below 60.1.0 (for ESR) or below 61.0 (for regular release)
  2. Identify WebExtensions with embedded experiments
    Navigate to about:support in Firefox, scroll to Extensions, or manually inspect the profile folder (typically ~/.mozilla/firefox/*.default) for extensions subfolder. Look for extensions containing experiment.jsm or experiment.js files which indicate embedded experiments.
    Affected if Any extension with embedded experiment modules is installed and enabled
  3. Review extension permissions
    Navigate to about:addons in Firefox, click the gear icon for each extension and select 'Manage Extension in Debug Mode' or inspect the manifest.json file directly in the extension folder. Check for permissions requesting '*://*/*' or '<all_urls>' access.
    Affected if Extensions have overly broad permissions combined with embedded experiment code
  4. Check for unauthorized extension behavior
    Monitor network connections or review extension activity through Browser Toolbox (Ctrl+Shift+Alt+I). Look for unexpected data exfiltration or unauthorized API calls.
    Affected if Extensions are making privileged API calls beyond their stated purpose

If Firefox version is below 60.1.0 (ESR) or 61.0 (regular) AND WebExtensions with embedded experiments are installed, the environment is vulnerable to privilege escalation.

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.

dbcve · scoped
Upgrade available Upgrade to 60.1.0 / 61.0 or later
Fixed in 60.1.061.0
Interim mitigation

Update Firefox to version 61 or Firefox ESR to 60.1 or later to obtain the patched version. Review installed extensions for suspicious behavior.

Recommended fix High confidence

Firefox ESR 60.1.0+ or Firefox 61.0+

  1. Check current Firefox version by navigating to about:support or running: firefox --version
  2. For Ubuntu/Linux systems, update via package manager: sudo apt-get update && sudo apt-get upgrade firefox
  3. Alternatively, download the latest Firefox from https://www.mozilla.org/firefox/download/
  4. Ensure the updated version is 60.1.0 or higher for ESR, or 61.0 or higher for regular Firefox
  5. Restart Firefox after update to ensure the new version is active
  6. Verify the fix by checking about:support shows the updated version
Caveat Minimal risk; some older extensions may be incompatible with newer Firefox versions, but security update is critical

Generated from the published advisory — verify against the referenced sources before acting.

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
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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-2018-12369 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