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FirefoxWeb browser · Mozilla

CVE-2011-2981

HIGH · 9.3 CVSS v2.0 Published 2011-08-18
Fix available
A fix is available. Upgrade to after 3.6.19 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
The event-management implementation in Mozilla Firefox before 3.6.20, SeaMonkey 2.x, Thunderbird 3.x before 3.1.12, and possibly other products does not properly select the context for script to run in, which allows remote attackers to bypass the Same Origin Policy or execute arbitrary JavaScript code with chrome privileges 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

The event-management implementation in Mozilla Firefox before 3.6.20, SeaMonkey 2.x, and Thunderbird 3.x before 3.1.12 fails to properly select the context for script execution. This allows remote attackers to bypass the Same Origin Policy or execute arbitrary JavaScript code with chrome privileges via a crafted website.

MitigationApply vendor-supplied patches by updating affected Mozilla products (Firefox to 3.6.20+, Thunderbird to 3.1.12+, SeaMonkey 2.x to patched version) to remediate the context selection flaw that enables Same Origin Policy bypass and chrome privilege JavaScript execution.

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:<= 3.6.19= 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= 1.5= 1.5.0.1
SeamonkeyApplication
Affected:= 2.0= 2.0.1= 2.0.2= 2.0.3= 2.0.4= 2.0.5= 2.0.6= 2.0.7= 2.0.8= 2.0.9= 2.0.10= 2.0.11
ThunderbirdApplication
Affected:= 3.0= 3.0.1= 3.0.2= 3.0.3= 3.0.4= 3.0.5= 3.0.6= 3.0.7= 3.0.8= 3.0.9= 3.0.10= 3.0.11

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
    Check for Firefox, SeaMonkey, or Thunderbird on the system. On Windows, examine Programs and Features or check common installation paths (C:\Program Files\Mozilla Firefox, C:\Program Files\SeaMonkey, C:\Program Files\Mozilla Thunderbird). On Linux, use package manager commands like dpkg -l or rpm -qa.
    Affected if Any of the three affected products (Firefox, SeaMonkey, Thunderbird) are installed
  2. Determine Firefox version
    For Firefox: Run 'firefox -v' from command line, or open Firefox and go to Help > About Firefox. Note the full version number (e.g., 3.6.19, 3.6.18, etc.).
    Affected if Version is 3.6.19 or lower, OR version is 1.0.x (1.0 through 1.0.8), OR version is 1.5.x (1.5 or 1.5.0.1)
  3. Determine SeaMonkey version
    For SeaMonkey: Run 'seamonkey -v' from command line, or open SeaMonkey and go to Help > About SeaMonkey. Note the full version number.
    Affected if Version starts with 2.0 and falls between 2.0 and 2.0.11 inclusive
  4. Determine Thunderbird version
    For Thunderbird: Run 'thunderbird -v' from command line, or open Thunderbird and go to Help > About Thunderbird. Note the full version number.
    Affected if Version starts with 3.0 and falls between 3.0 and 3.0.11 inclusive

A user is affected if Firefox version is 3.6.19 or lower, or a 1.0.x/1.5.x version; or SeaMonkey is any 2.0.x through 2.0.11; or Thunderbird is any 3.0.x through 3.0.11.

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 3.6.19
Interim mitigation

Apply vendor-supplied patches by updating affected Mozilla products (Firefox to 3.6.20+, Thunderbird to 3.1.12+, SeaMonkey 2.x to patched version) to remediate the context selection flaw that enables Same Origin Policy bypass and chrome privilege JavaScript execution.

Recommended fix High confidence

Firefox 3.6.20, SeaMonkey 2.0.4, Thunderbird 3.1.12 (or migrate to current supported versions of these products)

  1. 1. Identify the installed Mozilla product (Firefox, SeaMonkey, or Thunderbird) and current version
  2. 2. For Firefox: Download and install Firefox 3.6.20 or later from mozilla.org
  3. 3. For SeaMonkey: Download and install SeaMonkey 2.0.4 or later from mozilla.org
  4. 4. For Thunderbird: Download and install Thunderbird 3.1.12 or later from mozilla.org
  5. 5. After upgrade, verify the installed version matches or exceeds the fixed release
  6. 6. Restart the application and confirm it launches without errors
Caveat These are very old legacy versions; upgrading may require data migration and users should back up profiles. Consider migrating to modern Firefox/Thunderbird releases as these legacy versions are no longer supported.

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

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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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-2011-2981 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