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FirefoxWeb browser · Mozilla

CVE-2017-7767

MEDIUM · 5.5 CVSS v3.0 Published 2018-06-11
Fix available
A fix is available. Upgrade to 52.2.0 / 54.0 or later.
See remediation →
57/100
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
The Mozilla Maintenance Service can be invoked by an unprivileged user to overwrite arbitrary files with junk data using the Mozilla Windows Updater, which runs with the Maintenance Service's 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 Mozilla Maintenance Service allows an unprivileged Windows user to invoke the Mozilla Windows Updater to overwrite arbitrary files with junk data, as the updater runs with the Maintenance Service's elevated privileges.

MitigationUpgrade Firefox to version 54 or later (or Firefox ESR to 52.2 or later). Since this requires local system access, ensure workstations follow least-privilege principles and restrict local admin rights.

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
None
Integrity
High
Availability
None

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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. Identify if Firefox is installed on Windows
    Check for Firefox installation directory at C:\Program Files\Mozilla Firefox\ or C:\Program Files (x86)\Mozilla Firefox\. Alternatively, check the Windows Registry under HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla\Mozilla Firefox or HKEY_CURRENT_USER\SOFTWARE\Mozilla\Mozilla Firefox for the version value.
    Affected if Firefox is present on the Windows system.
  2. Determine the installed Firefox version
    Read the version from the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla\Mozilla Firefox\CurrentVersion (or the version key under the current version entry), or right-click firefox.exe in the installation folder and view Properties > Details for the File Version.
    Affected if The version is less than 54.0 (or less than 52.2.0 for ESR releases).
  3. Verify the Mozilla Maintenance Service is present
    Check for the service by opening Services.msc and looking for 'Mozilla Maintenance Service', or check the registry under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MozillaMaintenance. Also verify the updater executable exists at C:\Program Files\Mozilla Firefox\maintenanceservice.exe.
    Affected if The Mozilla Maintenance Service is installed on the system.
  4. Confirm the system is Windows
    Run 'systeminfo' or check the OS name in the system properties. This vulnerability only affects Windows systems with the Mozilla Maintenance Service.
    Affected if The operating system is Windows and the Mozilla Maintenance Service is present.

A user is affected if they are running Firefox versions prior to 54.0 (or prior to 52.2.0 ESR) on Windows with the Mozilla Maintenance Service 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 52.2.0 / 54.0 or later
Fixed in 52.2.054.0
Interim mitigation

Upgrade Firefox to version 54 or later (or Firefox ESR to 52.2 or later). Since this requires local system access, ensure workstations follow least-privilege principles and restrict local admin rights.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
4.0 hours of engineering $750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,200.

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-2017-7767 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