CVE-2009-1571

CVE-2009-1571 is a critical-severity vulnerability in Mozilla Firefox with a CVSS 2.0 base score of 10.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-94.

Key facts

• Severity: Critical (CVSS 2.0 base score 10.0)
• EPSS exploit prediction: 6% (93rd percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-94
• Affected product: Mozilla Firefox
• Published: 2010-02-22
• Last modified: 2026-06-16

Description

Use-after-free vulnerability in the HTML parser in Mozilla Firefox 3.0.x before 3.0.18 and 3.5.x before 3.5.8, Thunderbird before 3.0.2, and SeaMonkey before 2.0.3 allows remote attackers to execute arbitrary code via unspecified method calls that attempt to access freed objects in low-memory situations.

Frequently asked questions

What is CVE-2009-1571?

Use-after-free vulnerability in the HTML parser in Mozilla Firefox 3.0.x before 3.0.18 and 3.5.x before 3.5.8, Thunderbird before 3.0.2, and SeaMonkey before 2.0.3 allows remote attackers to execute arbitrary code via unspecified method calls that attempt to access freed objects in low-memory situations.

How severe is CVE-2009-1571?

CVE-2009-1571 has a CVSS 2.0 base score of 10.0, rated critical severity.

Is CVE-2009-1571 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-1571?

CVE-2009-1571 primarily affects Mozilla Firefox. In total, 67 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2009-1571?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2009-1571 published?

CVE-2009-1571 was published on 2010-02-22 and last updated on 2026-06-16.

References

• http://lists.fedoraproject.org/pipermail/package-announce/2010-February/035346.html
• http://lists.fedoraproject.org/pipermail/package-announce/2010-February/035367.html
• http://lists.fedoraproject.org/pipermail/package-announce/2010-February/035426.html
• http://lists.fedoraproject.org/pipermail/package-announce/2010-March/036097.html
• http://lists.fedoraproject.org/pipermail/package-announce/2010-March/036132.html
• http://lists.opensuse.org/opensuse-security-announce/2010-03/msg00001.html
• http://secunia.com/advisories/37242
• http://secunia.com/advisories/38770
• http://secunia.com/advisories/38772
• http://secunia.com/advisories/38847
• http://secunia.com/secunia_research/2009-45/
• http://www.debian.org/security/2010/dsa-1999
• http://www.mandriva.com/security/advisories?name=MDVSA-2010:042
• http://www.mandriva.com/security/advisories?name=MDVSA-2010:051
• http://www.mozilla.org/security/announce/2010/mfsa2010-03.html
• http://www.redhat.com/support/errata/RHSA-2010-0112.html
• http://www.redhat.com/support/errata/RHSA-2010-0113.html
• http://www.redhat.com/support/errata/RHSA-2010-0153.html
• http://www.redhat.com/support/errata/RHSA-2010-0154.html
• http://www.securityfocus.com/archive/1/509585/100/0/threaded
• http://www.ubuntu.com/usn/USN-895-1
• http://www.ubuntu.com/usn/USN-896-1
• http://www.vupen.com/english/advisories/2010/0405
• http://www.vupen.com/english/advisories/2010/0650
• https://bugzilla.mozilla.org/show_bug.cgi?id=526500
• https://exchange.xforce.ibmcloud.com/vulnerabilities/56361
• https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11227
• https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A8615

Affected products (67)

• cpe:2.3:a:mozilla:firefox:3.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0:alpha:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0:beta2:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0:beta5:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.2:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.3:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.4:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.5:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.6:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.7:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.8:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.9:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.10:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.11:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.12:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.13:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.14:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.15:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.0.17:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.5:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.5.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.5.2:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.5.3:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.5.4:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.5.5:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.5.6:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:3.5.7:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:1.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:1.0:alpha:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:1.0:beta:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:1.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:1.0.2:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:1.0.3:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:1.0.4:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:1.0.5:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:1.0.6:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:1.0.7:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:1.0.8:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:1.0.9:*:*:*:*:*:*:*

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