CVE-2012-1940

CVE-2012-1940 is a critical-severity vulnerability in Mozilla Firefox with a CVSS 2.0 base score of 9.3. 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-399.

Key facts

Description

Use-after-free vulnerability in the nsFrameList::FirstChild function in Mozilla Firefox 4.x through 12.0, Firefox ESR 10.x before 10.0.5, Thunderbird 5.0 through 12.0, Thunderbird ESR 10.x before 10.0.5, and SeaMonkey before 2.10 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption and application crash) by changing the size of a container of absolutely positioned elements in a column.

Frequently asked questions

What is CVE-2012-1940?
Use-after-free vulnerability in the nsFrameList::FirstChild function in Mozilla Firefox 4.x through 12.0, Firefox ESR 10.x before 10.0.5, Thunderbird 5.0 through 12.0, Thunderbird ESR 10.x before 10.0.5, and SeaMonkey before 2.10 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption and application crash) by changing the size of a container of absolutely positioned elements in a column.
How severe is CVE-2012-1940?
CVE-2012-1940 has a CVSS 2.0 base score of 9.3, rated critical severity.
Is CVE-2012-1940 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (90th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2012-1940?
CVE-2012-1940 primarily affects Mozilla Firefox. In total, 168 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2012-1940?
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-2012-1940 published?
CVE-2012-1940 was published on 2012-06-05 and last updated on 2026-06-16.

References

Affected products (168)

More vulnerabilities in Mozilla Firefox

All CVEs affecting Mozilla Firefox →

Other CWE-399 (Resource Management Errors) vulnerabilities

Browse all CWE-399 (Resource Management Errors) vulnerabilities →