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FirefoxWeb browser · Mozilla

CVE-2018-12397

HIGH · 7.1 CVSS v3.0 Published 2019-02-28
Fix available
A fix is available. Upgrade to 60.3.0 / 63.0 or later.
See remediation →
73/100
Remediation priority · Elevated
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
A WebExtension can request access to local files without the warning prompt stating that the extension will "Access your data for all websites" being displayed to the user. This allows extensions to run content scripts in local pages without permission warnings when a local file is opened. This vulnerability affects Firefox ESR < 60.3 and Firefox < 63.

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

A vulnerability in Firefox allows WebExtensions to access local files without displaying the standard permission warning 'Access your data for all websites'. This enables malicious extensions to run content scripts on local HTML pages without user consent, exposing sensitive local data.

MitigationUpgrade Firefox to version 60.3 (ESR) or 63 or later to apply the security patch that enforces proper permission warnings for local file access.

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:< 60.3.0< 63.0
Enterprise Linux DesktopOperating system
Affected:= 6.0= 7.0
Enterprise Linux ServerOperating system
Affected:= 6.0= 7.0
Enterprise Linux Server EusOperating system
Affected:= 7.5
Enterprise Linux WorkstationOperating system
Affected:= 6.0= 7.0
Debian LinuxOperating system
Affected:= 8.0= 9.0
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 18.04= 18.10

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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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
    Open Firefox, navigate to Help > About Firefox, or run 'firefox --version' from command line. Alternatively, check /usr/lib/firefox or the package manager (rpm -q firefox or dpkg -l firefox)
    Affected if Version is below 60.3.0 (ESR) or below 63.0 (release)
  2. Verify WebExtension support is enabled
    Navigate to about:config in Firefox address bar and check that the preference 'extensions.webextensions.enabled' is set to true
    Affected if WebExtensions are enabled and Firefox version is vulnerable
  3. Check for WebExtensions with file access permissions
    Navigate to about:addons, click on the gear icon, select 'Debug Add-ons', then 'Load Temporary Add-on' to examine installed extensions. Check extension manifest.json files for 'file' permission or 'file://' URL patterns in content_scripts matches
    Affected if Any WebExtension with file access permissions is installed and Firefox version is vulnerable
  4. Test local file access behavior
    Create a local HTML file with script content, then install a test WebExtension with file:// pattern in content_scripts. Load it as a temporary add-on and observe whether it runs on the local file without displaying the permission warning 'Access your data for all websites'
    Affected if Content scripts run on local file:// URLs without triggering the expected permission warning

If Firefox version is below 60.3.0 or below 63.0 AND WebExtensions are enabled, the environment is affected by this vulnerability where malicious extensions could access local files without user consent.

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 60.3.0 / 63.0 or later
Fixed in 60.3.063.0
Interim mitigation

Upgrade Firefox to version 60.3 (ESR) or 63 or later to apply the security patch that enforces proper permission warnings for local file access.

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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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-2018-12397 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