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FirefoxWeb browser · Mozilla

CVE-2009-3075

HIGH · 10.0 CVSS v2.0 Published 2009-09-10
Fix available
A fix is available. Upgrade to after 3.0.13 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
Multiple unspecified vulnerabilities in the JavaScript engine in Mozilla Firefox before 3.0.14 and 3.5.x before 3.5.2, Thunderbird before 2.0.0.24, and SeaMonkey before 1.1.19 allow remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via vectors related to use of mutable strings in the js_StringReplaceHelper function in js/src/jsstr.cpp, and unknown vectors.

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 critical memory corruption vulnerability in Mozilla's JavaScript engine (js_StringReplaceHelper function in jsstr.cpp) where improper handling of mutable strings allows remote attackers to crash the browser or potentially execute arbitrary code via malicious JavaScript in web pages or emails.

MitigationUpgrade affected products to patched versions: Firefox 3.0.14/3.5.2+, Thunderbird 2.0.0.24+, or SeaMonkey 1.1.19+. For legacy systems that cannot upgrade, consider disabling JavaScript in mail clients and restricting browser access to untrusted content.

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:<= 3.0.13= 0.1= 0.2= 0.3= 0.4= 0.5= 0.6= 0.6.1= 0.7= 0.7.1= 0.8= 0.9

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. Determine Firefox version
    Navigate to Help > About Mozilla Firefox, or enter 'about:support' in the address bar, or run 'firefox -version' from command line
    Affected if Version is 3.0.13 or lower, or falls within versions 0.1 through 0.9 (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.6.1, 0.7, 0.7.1, 0.8, 0.9)
  2. Check for Thunderbird version
    Navigate to Help > About Thunderbird, or run 'thunderbird -version' from command line
    Affected if Version is 2.0.0.23 or lower (vulnerable if older than 2.0.0.24)
  3. Check for SeaMonkey version
    Navigate to Help > About SeaMonkey, or run 'seamonkey -version' from command line
    Affected if Version is 1.1.18 or lower (vulnerable if older than 1.1.19)
  4. Verify JavaScript is enabled in Firefox
    Go to Tools > Options > Content (or enter 'about:config' and search for 'javascript.enabled'), confirm the setting is true
    Affected if JavaScript is enabled (the exploit requires JavaScript to be active to trigger the vulnerability)

If the installed Firefox version is 3.0.13 or lower (or in the 0.x range), or Thunderbird/SeaMonkey are below their patched versions, and JavaScript is enabled in the application, the environment is vulnerable to CVE-2009-3075.

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 3.0.13
Interim mitigation

Upgrade affected products to patched versions: Firefox 3.0.14/3.5.2+, Thunderbird 2.0.0.24+, or SeaMonkey 1.1.19+. For legacy systems that cannot upgrade, consider disabling JavaScript in mail clients and restricting browser access to untrusted content.

Recommended fix High confidence

Firefox 3.0.14 (minimum fix) or Firefox 3.5.2 (minimum fix for 3.5.x branch); recommended: latest stable Firefox

  1. 1. Back up any important data and bookmarks from the current Firefox installation
  2. 2. Download the latest stable Firefox release from the official Mozilla website (https://www.mozilla.org/firefox/)
  3. 3. Uninstall the current Firefox version (3.0.13 or earlier, or 3.5.x)
  4. 4. Install the latest Firefox version
  5. 5. Restore bookmarks and preferences from the backup
  6. 6. Verify the installation by checking Help > About Firefox to confirm the version
Caveat Modern Firefox has significant UI and extension compatibility changes compared to 3.0.x/3.5.x; some legacy extensions may not be compatible with current Firefox

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

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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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-2009-3075 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