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FirefoxWeb browser · Mozilla

CVE-2011-0066

HIGH · 10.0 CVSS v2.0 Published 2011-05-07
Fix available
A fix is available. Upgrade to after 2.0.13 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
Use-after-free vulnerability in Mozilla Firefox before 3.5.19 and 3.6.x before 3.6.17, and SeaMonkey before 2.0.14, allows remote attackers to execute arbitrary code via vectors related to OBJECT's mObserverList.

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 use-after-free vulnerability in Mozilla Firefox (versions before 3.5.19 and 3.6.x before 3.6.17) and SeaMonkey (before 2.0.14) allows remote attackers to execute arbitrary code by manipulating the OBJECT element's mObserverList, causing the browser to reference freed memory.

MitigationUpgrade affected browsers to Firefox 3.5.19+, Firefox 3.6.17+, or SeaMonkey 2.0.14+ to patch the use-after-free vulnerability in the OBJECT element's observer list.

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:= 3.6= 3.6.2= 3.6.3= 3.6.4= 3.6.6= 3.6.7= 3.6.8= 3.6.9= 3.6.10= 3.6.11= 3.6.12= 3.6.13
SeamonkeyApplication
Affected:<= 2.0.13= 1.0= 1.0.1= 1.0.2= 1.0.3= 1.0.4= 1.0.5= 1.0.6= 1.0.7= 1.0.8= 1.0.9= 1.1

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
Low
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:L/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. Check Firefox version on Windows
    Open Firefox, click Help > About Firefox, or run 'firefox --version' from command line
    Affected if Version shows 3.6.x where x is less than 17, or 3.5.x where x is less than 19
  2. Check Firefox version on Linux
    Run 'firefox --version' in terminal or check the package manager (dpkg -l firefox or rpm -q firefox)
    Affected if Version is 3.6.x before 3.6.17, or 3.5.x before 3.5.19
  3. Check SeaMonkey version
    Open SeaMonkey, click Help > About SeaMonkey, or run 'seamonkey --version' from command line
    Affected if Version is 2.0.13 or earlier, or any 1.x version including 1.0 through 1.1
  4. Verify OBJECT element handling is in use
    The vulnerability exists in the core browser rendering of OBJECT elements (such as embedded content). This is a default browser feature that cannot be disabled.
    Affected if The browser is used to render any HTML page containing OBJECT elements - this is enabled by default in normal browsing

You are affected if you run Firefox versions 3.6.x before 3.6.17 (including 3.6, 3.6.2-3.6.13), any Firefox 3.5.x before 3.5.19, or SeaMonkey 2.0.13 or earlier (including all 1.x versions).

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 a release after 2.0.13
Interim mitigation

Upgrade affected browsers to Firefox 3.5.19+, Firefox 3.6.17+, or SeaMonkey 2.0.14+ to patch the use-after-free vulnerability in the OBJECT element's observer list.

Recommended fix High confidence

Firefox 3.6.17 (or Firefox 3.5.19 for 3.5.x branch); SeaMonkey 2.0.14; or migrate to modern maintained versions (Firefox ESR 78.x+/SeaMonkey 2.53.x+)

  1. 1. Identify the currently installed Firefox or SeaMonkey version using Help > About or by running 'firefox --version' or 'seamonkey --version' in the terminal.
  2. 2. For Firefox 3.6.x users: Download and install Firefox 3.6.17 (the last security update for the Firefox 3.6 branch) from archive.mozilla.org or your distribution's repositories.
  3. 3. For Firefox 3.5.x users: Download and install Firefox 3.5.19 from Mozilla's archives.
  4. 4. For SeaMonkey users: Download and install SeaMonkey 2.0.14 from the SeaMonkey project website or your distribution's repositories.
  5. 5. After installation, verify the version by checking Help > About to confirm the correct version is installed.
  6. 6. Consider migrating to a maintained browser version (Firefox ESR 78.x or later, or SeaMonkey 2.53.x) as Firefox 3.6 and SeaMonkey 2.0 are end-of-life and no longer receive security updates.
Caveat Firefox 3.6.x and SeaMonkey 2.0.x are end-of-life and may have compatibility issues with modern websites; some legacy extensions and plugins may not work in newer versions

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
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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-2011-0066 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