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FirefoxWeb browser · Mozilla

CVE-2015-0833

MEDIUM · 6.9 CVSS v2.0 Published 2015-02-25
Fix available
A fix is available. Upgrade to after 35.0.1 or later.
See remediation →
74/100
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
Multiple untrusted search path vulnerabilities in updater.exe in Mozilla Firefox before 36.0, Firefox ESR 31.x before 31.5, and Thunderbird before 31.5 on Windows, when the Maintenance Service is not used, allow local users to gain privileges via a Trojan horse DLL in (1) the current working directory or (2) a temporary directory, as demonstrated by bcrypt.dll.

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 DLL hijacking vulnerability in Firefox and Thunderbird's updater.exe on Windows. When the Maintenance Service is not installed, the updater loads DLLs from untrusted locations - specifically the current working directory or the system's temporary directory. An attacker with local access can place a malicious DLL (e.g., bcrypt.dll) in one of these locations, and it will be loaded with elevated privileges when the updater runs.

MitigationUpgrade to Firefox 36.0+, Firefox ESR 31.5+, or Thunderbird 31.5+. Alternatively, ensure the Mozilla Maintenance Service is installed, which avoids this vulnerable code path.

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:<= 35.0.1= 0.1= 0.2= 0.3= 0.4= 0.5= 0.6= 0.6.1= 0.7= 0.7.1= 0.8= 0.9
Firefox EsrWeb browser
Affected:= 31.1= 31.2= 31.3= 31.4= 31.5
EvergreenOperating system
Affected:= 11.4
OpensuseOperating system
Affected:= 13.1= 13.2
ThunderbirdApplication
Affected:<= 31.4= 31.0= 31.1.2= 31.2= 31.3

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
M
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:L/AC:M/Au:N/C:C/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 operating system
    Check if the system is running Windows (this vulnerability only affects Windows). Run 'systeminfo' or check OS via 'winver' or System Properties.
    Affected if System is NOT running Windows - the vulnerability does not apply to Linux or macOS.
  2. Identify installed Mozilla product
    Check for Firefox or Thunderbird installation. Look in Program Files (e.g., C:\Program Files\Mozilla Firefox or C:\Program Files\Mozilla Thunderbird) or check Start Menu shortcuts.
    Affected if Neither Firefox nor Thunderbird is installed - no action needed.
  3. Check installed Firefox or Thunderbird version
    For Firefox: Run 'firefox -v' or check the about dialog (Help > About Firefox). For Thunderbird: Run 'thunderbird -v' or check the about dialog (Help > About Thunderbird). Compare the version against the affected ranges: Firefox <=35.0.1, Firefox ESR 31.1-31.5, Thunderbird <=31.4.
    Affected if Version is HIGHER than 35.0.1 for Firefox, HIGHER than 31.5 for ESR, or HIGHER than 31.4 for Thunderbird - not affected.
  4. Verify Mozilla Maintenance Service status
    Check if the Mozilla Maintenance Service is installed. Look in Windows Services (services.msc) for 'Mozilla Maintenance Service' or check Add/Remove Programs. Also verify existence of 'C:\Program Files\Mozilla Maintenance Service\maintenanceservice.exe'.
    Affected if The Mozilla Maintenance Service IS installed - the vulnerable code path is not triggered, so not affected.
  5. Confirm updater.exe presence
    Locate updater.exe in the Firefox or Thunderbird installation directory (e.g., C:\Program Files\Mozilla Firefox\updater.exe). The vulnerability exists in this executable when Maintenance Service is absent.
    Affected if updater.exe does not exist or product is not installed - not affected.

Environment is affected if running Windows with Firefox <=35.0.1 (or ESR 31.1-31.5) or Thunderbird <=31.4 AND the Mozilla Maintenance Service is NOT 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 a release after 35.0.1
Interim mitigation

Upgrade to Firefox 36.0+, Firefox ESR 31.5+, or Thunderbird 31.5+. Alternatively, ensure the Mozilla Maintenance Service is installed, which avoids this vulnerable code path.

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-2015-0833 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