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FirefoxWeb browser · Mozilla

CVE-2018-18494

MEDIUM · 6.5 CVSS v3.0 Published 2019-02-28
Fix available
A fix is available. Upgrade to 60.4.0 / 64.0 or later.
See remediation →
72/100
Remediation priority · Elevated
Remotely reachable No privileges

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 same-origin policy violation allowing the theft of cross-origin URL entries when using the Javascript location property to cause a redirection to another site using performance.getEntries(). This is a same-origin policy violation and could allow for data theft. This vulnerability affects Thunderbird < 60.4, Firefox ESR < 60.4, and Firefox < 64.

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

This is a same-origin policy (SOP) bypass vulnerability in Firefox and Thunderbird. An attacker can exploit the JavaScript location property combined with performance.getEntries() to steal cross-origin URL entries during redirection, allowing unauthorized access to sensitive URL information that should be protected by the SOP.

MitigationUpdate affected browsers to Firefox 64+, Firefox ESR 60.4+, or Thunderbird 60.4+ to obtain the patched versions that enforce proper same-origin restrictions on the performance API.

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:< 60.4.0< 64.0
Debian LinuxOperating system
Affected:= 8.0= 9.0
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 18.04= 18.10
Enterprise Linux DesktopOperating system
Affected:= 6.0= 7.0
Enterprise Linux ServerOperating system
Affected:= 6.0= 7.0
Enterprise Linux Server AusOperating system
Affected:= 7.6
Enterprise Linux Server EusOperating system
Affected:= 7.6
Enterprise Linux Server TusOperating system
Affected:= 7.6

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
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 checks

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

  1. Identify installed browser
    Check if Mozilla Firefox or Thunderbird is installed on the system. On Linux, run: dpkg -l | grep -i firefox or rpm -qa | grep -i firefox for Debian/RHEL systems. On Windows, check Program Files for Mozilla Firefox or Mozilla Thunderbird folders.
    Affected if Firefox or Thunderbird is installed
  2. Determine Firefox version
    Run: firefox --version. Alternatively, in Firefox address bar, enter: about:support to view version details.
    Affected if Version is less than 60.4.0 or between 60.4.0 and 64.0 (excluding 64.0 itself)
  3. Determine Thunderbird version
    Run: thunderbird --version. Alternatively, in Thunderbird, go to Help > About Thunderbird.
    Affected if Version is less than 60.4.0 or between 60.4.0 and 64.0 (excluding 64.0 itself)
  4. Check Linux distribution packages
    On Debian/Ubuntu: dpkg -l | grep -i firefox-thunderbird. On RHEL: rpm -qa | grep -i firefox. Check the installed package version against the affected Debian 8/9 or Ubuntu 14.04/16.04/18.04/18.10 versions.
    Affected if The packaged browser version matches the vulnerable distribution versions

You are affected if Firefox or Thunderbird version is less than 60.4.0 or falls between 60.4.0 and 64.0, or if a Linux distribution package from the affected versions (Debian 8/9, Ubuntu 14.04-18.10, RHEL 6/7) is installed.

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 60.4.0 / 64.0 or later
Fixed in 60.4.064.0
Interim mitigation

Update affected browsers to Firefox 64+, Firefox ESR 60.4+, or Thunderbird 60.4+ to obtain the patched versions that enforce proper same-origin restrictions on the performance API.

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-2018-18494 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