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FirefoxWeb browser · Mozilla

CVE-2017-7766

HIGH · 7.8 CVSS v3.0 Published 2018-06-11
Fix available
A fix is available. Upgrade to 52.2.0 / 54.0 or later.
See remediation →
80/100
Remediation priority · High
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
An attack using manipulation of "updater.ini" contents, used by the Mozilla Windows Updater, and privilege escalation through the Mozilla Maintenance Service to allow for arbitrary file execution and deletion by the Maintenance Service, which has privileged access. Note: This attack requires local system access and only affects Windows. Other operating systems are not affected. This vulnerability affects Firefox ESR < 52.2 and Firefox < 54.

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 local privilege escalation vulnerability in the Mozilla Maintenance Service on Windows allows manipulation of updater.ini to cause arbitrary file execution and deletion with elevated privileges. The attack requires local system access and targets the Windows updater mechanism.

MitigationUpdate Firefox to version 54+ or Firefox ESR to 52.2+ to patch the vulnerability. Alternatively, disable or restrict the Mozilla Maintenance Service if updates are not immediately possible.

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:< 52.2.0< 54.0

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
High

CVSS:3.0/AV:L/AC:L/PR:L/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. Identify if Firefox is installed on the Windows system
    Check for Firefox installation directories (typically in Program Files or Program Files (x86)) or query the system for installed software using 'Get-ItemProperty' in registry at HKLM:\SOFTWARE\Mozilla\Mozilla Firefox or via Windows installed programs list
    Affected if Firefox is found to be installed on the system
  2. Determine the installed Firefox version
    Run 'firefox -v' from the Firefox installation directory, or read the version from the application.ini file in the Firefox program folder, or check the Windows registry version key under the Mozilla Firefox registry entry
    Affected if The installed version is lower than 54.0 (or lower than 52.2.0 for Firefox ESR releases)
  3. Verify the Mozilla Maintenance Service is present
    Check for the existence of the Mozilla Maintenance Service directory and updater.exe, typically located in 'C:\Program Files\Mozilla Maintenance Service\' or within the Firefox installation folder
    Affected if The Mozilla Maintenance Service directory and its updater component exist on the system
  4. Locate and inspect updater.ini configuration file
    Find updater.ini in the Mozilla Maintenance Service directory (commonly at 'C:\Program Files\Mozilla Maintenance Service\updater.ini' or in the Firefox updater directory) and check its contents for any anomalies or unauthorized modifications
    Affected if The updater.ini file exists and is writable or has been modified from its expected default configuration

A system is affected if Firefox versions below 54.0 (or below 52.2.0 for ESR) are installed on Windows alongside the Mozilla Maintenance Service with a modifiable updater.ini file.

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 52.2.0 / 54.0 or later
Fixed in 52.2.054.0
Interim mitigation

Update Firefox to version 54+ or Firefox ESR to 52.2+ to patch the vulnerability. Alternatively, disable or restrict the Mozilla Maintenance Service if updates are not immediately possible.

Fix this in Firefox Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.

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-2017-7766 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