CVE-2012-3959

CVE-2012-3959 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-416.

Key facts

• Severity: Critical (CVSS 2.0 base score 10.0)
• EPSS exploit prediction: 5% (91st percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-416
• Affected product: Mozilla Firefox
• Published: 2012-08-29
• Last modified: 2026-06-16

Description

Use-after-free vulnerability in the nsRangeUpdater::SelAdjDeleteNode function in Mozilla Firefox before 15.0, Firefox ESR 10.x before 10.0.7, Thunderbird before 15.0, Thunderbird ESR 10.x before 10.0.7, and SeaMonkey before 2.12 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) via unspecified vectors.

Frequently asked questions

What is CVE-2012-3959?

Use-after-free vulnerability in the nsRangeUpdater::SelAdjDeleteNode function in Mozilla Firefox before 15.0, Firefox ESR 10.x before 10.0.7, Thunderbird before 15.0, Thunderbird ESR 10.x before 10.0.7, and SeaMonkey before 2.12 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) via unspecified vectors.

How severe is CVE-2012-3959?

CVE-2012-3959 has a CVSS 2.0 base score of 10.0, rated critical severity.

Is CVE-2012-3959 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2012-3959?

CVE-2012-3959 primarily affects Mozilla Firefox. In total, 25 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2012-3959?

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-2012-3959 published?

CVE-2012-3959 was published on 2012-08-29 and last updated on 2026-06-16.

References

• http://lists.opensuse.org/opensuse-security-announce/2012-08/msg00028.html
• http://lists.opensuse.org/opensuse-security-announce/2012-09/msg00011.html
• http://lists.opensuse.org/opensuse-security-announce/2012-09/msg00014.html
• http://rhn.redhat.com/errata/RHSA-2012-1210.html
• http://rhn.redhat.com/errata/RHSA-2012-1211.html
• http://www.debian.org/security/2012/dsa-2553
• http://www.debian.org/security/2012/dsa-2554
• http://www.debian.org/security/2012/dsa-2556
• http://www.mozilla.org/security/announce/2012/mfsa2012-58.html
• http://www.securityfocus.com/bid/55324
• http://www.ubuntu.com/usn/USN-1548-1
• http://www.ubuntu.com/usn/USN-1548-2
• http://www.xerox.com/download/security/security-bulletin/16287-4d6b7b0c81f7b/cert_XRX13-003_v1.0.pdf
• https://bugzilla.mozilla.org/show_bug.cgi?id=771994
• https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16805

Affected products (25)

• cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:seamonkey:*:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
• cpe:2.3:a:mozilla:thunderbird_esr:*:*:*:*:*:*:*:*
• cpe:2.3:o:opensuse:opensuse:12.2:*:*:*:*:*:*:*
• cpe:2.3:o:suse:linux_enterprise_desktop:10:sp4:*:*:-:*:*:*
• cpe:2.3:o:suse:linux_enterprise_desktop:11:sp2:*:*:*:*:*:*
• cpe:2.3:o:suse:linux_enterprise_server:10:sp4:*:*:-:*:*:*
• cpe:2.3:o:suse:linux_enterprise_server:11:sp2:*:*:*:-:*:*
• cpe:2.3:o:suse:linux_enterprise_server:11:sp2:*:*:*:vmware:*:*
• cpe:2.3:o:suse:linux_enterprise_software_development_kit:11:sp2:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_desktop:5.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_desktop:6.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_eus:6.3:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server:5.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server:6.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_server_eus:6.3:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_workstation:5.0:*:*:*:*:*:*:*
• cpe:2.3:o:redhat:enterprise_linux_workstation:6.0:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:10.04:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:11.04:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:11.10:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:esm:*:*:*
• cpe:2.3:o:debian:debian_linux:6.0:*:*:*:*:*:*:*
• cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:*

More vulnerabilities in Mozilla Firefox

• CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
• CVE-2026-4692 — Critical (CVSS 10.0): Sandbox escape in the Responsive Design Mode component. This vulnerability was fixed in Firefox 149, Firefox ESR…
• CVE-2026-4689 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component. This vulnerability was…
• CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…
• CVE-2026-2778 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. This vulnerability was fixed in…
• CVE-2026-2776 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability…

All CVEs affecting Mozilla Firefox →

Other CWE-416 (Use After Free) vulnerabilities

• CVE-2026-13782 — Critical (CVSS 10.0): Use after free in Browser in Google Chrome prior to 150.0.7871.47 allowed a remote attacker who had compromised the…
• CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
• CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…
• CVE-2025-24085 — Critical (CVSS 10.0): A use after free issue was addressed with improved memory management. This issue is fixed in iOS 18.3 and iPadOS 18.3,…
• CVE-2024-43102 — Critical (CVSS 10.0): Concurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of…
• CVE-2021-32495 — Critical (CVSS 10.0): Radare2 has a use-after-free vulnerability in pyc parser's get_none_object function. Attacker can read freed memory…

Browse all CWE-416 (Use After Free) vulnerabilities →