FirefoxWeb browser · Mozilla
CVE-2016-5295
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 · uneditedThis vulnerability allows an attacker to use the Mozilla Maintenance Service to escalate privilege by having the Maintenance Service invoke the Mozilla Updater to run malicious local files. This vulnerability requires local system access and is a variant of MFSA2013-44. Note: this issue only affects Windows operating systems. This vulnerability affects Firefox < 50.
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 confidenceThis is a local privilege escalation vulnerability in the Mozilla Maintenance Service on Windows. An attacker with local system access can exploit the service to invoke the Mozilla Updater to execute malicious local files instead of legitimate updates. This is a variant of MFSA2013-44 affecting Firefox versions prior to 50.
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
< 50.0CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Verify Windows operating systemConfirm the system is running Windows (this vulnerability only affects Windows environments). Check system properties or run 'systeminfo' command and look for OS Name containing 'Windows'.Affected if System is NOT running Windows - the vulnerability only affects Windows systems with Mozilla Maintenance Service.
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Identify Firefox installationLocate Firefox installation directory (typically C:\Program Files\Mozilla Firefox or C:\Program Files (x86)\Mozilla Firefox) and check the version.ini file, or run 'firefox --version' if available. Also check registry key HKLM\SOFTWARE\Mozilla\Mozilla Firefox\CurrentVersion or HKLM\SOFTWARE\WOW6432Node\Mozilla\Mozilla Firefox\CurrentVersion.Affected if Firefox is not installed on the Windows system.
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Compare Firefox version to affected rangeRead the installed Firefox version number and compare against 50.0. Versions below 50.0 (such as 49.x, 48.x, etc.) are vulnerable.Affected if Firefox version is 50.0 or higher - the vulnerability only affects versions below 50.0.
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Confirm Mozilla Maintenance Service presenceCheck Windows Services (services.msc) for 'Mozilla Maintenance Service' status, or check for the service binary at C:\Program Files\Mozilla Maintenance Service\maintenanceservice.exe or C:\Program Files (x86)\Mozilla Maintenance Service\maintenanceservice.exe.Affected if Mozilla Maintenance Service is not installed - the vulnerable component is not present.
A system is affected if it is running Windows with Firefox version below 50.0 AND the Mozilla Maintenance Service is installed and present on the system.
Generated from the published advisory. Verify against your own configuration.
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 data50.0
Upgrade Firefox to version 50 or later on all affected Windows systems to eliminate the vulnerable code path in the Maintenance Service.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,456.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-5295 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2016-5295 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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