CVE-2013-1720

CVE-2013-1720 is a medium-severity vulnerability in Mozilla Firefox with a CVSS 2.0 base score of 6.8. 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-119.

Key facts

• Severity: Medium (CVSS 2.0 base score 6.8)
• EPSS exploit prediction: 4% (89th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-119
• Affected product: Mozilla Firefox
• Published: 2013-09-18
• Last modified: 2026-06-16

Description

The nsHtml5TreeBuilder::resetTheInsertionMode function in the HTML5 Tree Builder in Mozilla Firefox before 24.0, Thunderbird before 24.0, and SeaMonkey before 2.21 does not properly maintain the state of the insertion-mode stack for template elements, which allows remote attackers to execute arbitrary code or cause a denial of service (heap-based buffer over-read) by triggering use of this stack in its empty state.

Frequently asked questions

What is CVE-2013-1720?

The nsHtml5TreeBuilder::resetTheInsertionMode function in the HTML5 Tree Builder in Mozilla Firefox before 24.0, Thunderbird before 24.0, and SeaMonkey before 2.21 does not properly maintain the state of the insertion-mode stack for template elements, which allows remote attackers to execute arbitrary code or cause a denial of service (heap-based buffer over-read) by triggering use of this stack in its empty state.

How severe is CVE-2013-1720?

CVE-2013-1720 has a CVSS 2.0 base score of 6.8, rated medium severity.

Is CVE-2013-1720 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2013-1720?

CVE-2013-1720 primarily affects Mozilla Firefox. In total, 119 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2013-1720?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2013-1720 published?

CVE-2013-1720 was published on 2013-09-18 and last updated on 2026-06-16.

References

• http://lists.fedoraproject.org/pipermail/package-announce/2013-September/115907.html
• http://lists.fedoraproject.org/pipermail/package-announce/2013-September/116610.html
• http://lists.fedoraproject.org/pipermail/package-announce/2013-September/117526.html
• http://lists.opensuse.org/opensuse-updates/2013-09/msg00055.html
• http://lists.opensuse.org/opensuse-updates/2013-09/msg00057.html
• http://lists.opensuse.org/opensuse-updates/2013-09/msg00059.html
• http://lists.opensuse.org/opensuse-updates/2013-09/msg00061.html
• http://www.mozilla.org/security/announce/2013/mfsa2013-77.html
• http://www.securityfocus.com/bid/62465
• http://www.ubuntu.com/usn/USN-1951-1
• http://www.ubuntu.com/usn/USN-1952-1
• https://bugzilla.mozilla.org/show_bug.cgi?id=888820
• https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A18617

Affected products (119)

• cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:19.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:19.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:19.0.2:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:20.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:20.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:21.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:22.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:firefox:23.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:thunderbird:17.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:thunderbird:17.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:thunderbird:17.0.2:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:thunderbird:17.0.3:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:thunderbird:17.0.4:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:thunderbird:17.0.5:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:thunderbird:17.0.6:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:thunderbird:17.0.7:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:thunderbird:17.0.8:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:*:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0:alpha_1:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0:alpha_2:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0:alpha_3:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0:beta_1:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0:beta_2:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0:rc1:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0:rc2:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0.2:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0.3:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0.4:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0.5:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0.6:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0.7:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0.8:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0.9:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0.10:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0.11:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:2.0.12:*:*:*:*:*:*:*

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