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FirefoxWeb browser · Mozilla

CVE-2015-4505

MEDIUM · 6.6 CVSS v2.0 Published 2015-09-24
Fix available
A fix is available. Upgrade to after 40.0.3 or later.
See remediation →
71/100
Remediation priority · Elevated
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
updater.exe in Mozilla Firefox before 41.0 and Firefox ESR 38.x before 38.3 on Windows allows local users to write to arbitrary files by conducting a junction attack and waiting for an update operation by the Mozilla Maintenance Service.

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

The Mozilla Maintenance Service updater.exe on Windows is vulnerable to a junction attack where a local unprivileged user can create a filesystem junction point and wait for the scheduled update operation to write files to arbitrary locations, achieving partial integrity compromise.

MitigationUpdate to Firefox 41.0 or later, or Firefox ESR 38.3 or later, to obtain the patched updater. Alternatively, disable or restrict the Mozilla Maintenance Service if updates are managed via other channels.

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:= 38.0= 38.0.1= 38.0.5= 38.1.0= 38.1.1= 38.2.0= 38.2.1<= 40.0.3

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
Authentication
None
Confidentiality
None
Integrity
Complete
Availability
Complete

AV:L/AC:L/Au:N/C:N/I:C/A:C

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. Confirm Windows environment
    Verify the operating system is Windows (this vulnerability only affects Windows systems)
    Affected if System is not Windows - the vulnerability does not apply to other OSes
  2. Identify Firefox version
    Open Firefox, go to Help > About Firefox, or check the version via registry at HKLM\SOFTWARE\Mozilla\Mozilla Firefox\CurrentVersion (or HKCU for per-user installs)
    Affected if Version is 38.0, 38.0.1, 38.0.5, 38.1.0, 38.1.1, 38.2.0, 38.2.1, or any version up to and including 40.0.3
  3. Locate Mozilla Maintenance Service
    Check for the presence of updater.exe in the Mozilla Maintenance Service installation directory, typically at C:\Program Files\Mozilla Maintenance Service\updater.exe or C:\Program Files (x86)\Mozilla Maintenance Service\updater.exe
    Affected if The Mozilla Maintenance Service updater.exe exists on the system (required component for the junction attack)

User is affected if running a Windows system with Firefox version 38.0 through 40.0.3 (inclusive) that has the Mozilla Maintenance Service installed and its scheduled update feature enabled.

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 a release after 40.0.3
Interim mitigation

Update to Firefox 41.0 or later, or Firefox ESR 38.3 or later, to obtain the patched updater. Alternatively, disable or restrict the Mozilla Maintenance Service if updates are managed via other channels.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA0.5 h
3.5 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

Free · runs locally
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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-2015-4505 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