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FirefoxWeb browser · Mozilla

CVE-2012-3991

HIGH · 9.3 CVSS v2.0 Published 2012-10-10
Fix available
A fix is available. Upgrade to 10.0.8 / 16.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable 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
Mozilla Firefox before 16.0, Firefox ESR 10.x before 10.0.8, Thunderbird before 16.0, Thunderbird ESR 10.x before 10.0.8, and SeaMonkey before 2.13 do not properly restrict JSAPI access to the GetProperty function, which allows remote attackers to bypass the Same Origin Policy and possibly have unspecified other impact via a crafted web site.

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 vulnerability in Mozilla Firefox ESR 10.x before 10.0.8, Thunderbird ESR 10.x before 10.0.8, and SeaMonkey before 2.13 allows remote attackers to bypass the Same Origin Policy by improperly restricting JSAPI access to the GetProperty function. A crafted website can exploit this to access sensitive information across origins.

MitigationUpdate affected Mozilla products to version 16.0 or later (Firefox/Thunderbird) or 2.13+ (SeaMonkey), or apply the ESR 10.0.8 patch. This is a client-side vulnerability requiring browser update.

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:< 10.0.8< 16.0
Ubuntu LinuxOperating system
Affected:= 10.04= 11.04= 11.10= 12.04
Enterprise Linux DesktopOperating system
Affected:= 5.0= 6.0
Enterprise Linux EusOperating system
Affected:= 6.3
Enterprise Linux ServerOperating system
Affected:= 5.0= 6.0
Enterprise Linux WorkstationOperating system
Affected:= 5.0= 6.0
Thunderbird EsrApplication
Affected:< 10.0.8
ThunderbirdApplication
Affected:< 16.0

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
Network
Complexity
M
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/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. Identify installed Mozilla product
    Determine which Mozilla browser or email client is installed: Firefox, Thunderbird, or SeaMonkey. Check the application name in the system menu, About dialog, or package manager.
    Affected if Any of Firefox, Thunderbird, or SeaMonkey is installed
  2. Check Firefox version
    For Firefox: enter 'about:support' in the address bar or run 'firefox --version' from command line. Look for the version number in the 'Application Basics' section.
    Affected if Version is below 16.0, or version is 10.x ESR series below 10.0.8
  3. Check Thunderbird version
    For Thunderbird: go to Help > About Thunderbird, or run 'thunderbird --version' from command line. Note the version number displayed.
    Affected if Version is below 16.0, or version is 10.x ESR series below 10.0.8
  4. Check SeaMonkey version
    For SeaMonkey: go to Help > About SeaMonkey, or run 'seamonkey --version' from command line. Note the version number displayed.
    Affected if Version is below 2.13

If the installed Firefox, Thunderbird, or SeaMonkey version is below 16.0 (or below 10.0.8 for ESR 10.x series) or SeaMonkey is below 2.13, the environment is affected by this Same Origin Policy bypass vulnerability.

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.

dbcve · scoped
Upgrade available Upgrade to 10.0.8 / 16.0 or later
Fixed in 10.0.816.0
Interim mitigation

Update affected Mozilla products to version 16.0 or later (Firefox/Thunderbird) or 2.13+ (SeaMonkey), or apply the ESR 10.0.8 patch. This is a client-side vulnerability requiring browser update.

Recommended fix High confidence

Firefox 16.0 (or Firefox ESR 10.0.8); Thunderbird 16.0 (or Thunderbird ESR 10.0.8); SeaMonkey 2.13

  1. Upgrade Firefox to version 16.0 or later (or Firefox ESR 10.0.8 or later if requiring ESR)
  2. Upgrade Thunderbird to version 16.0 or later (or Thunderbird ESR 10.0.8 or later if requiring ESR)
  3. Upgrade SeaMonkey to version 2.13 or later
  4. After upgrading, verify the installation by checking About/ Help > About to confirm the version number
Caveat Minor Mozilla version upgrades typically do not introduce breaking changes; however, some older add-ons/extensions may be incompatible with the new version

Generated from the published advisory — verify against the referenced sources before acting.

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-2012-3991 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