CVE-2012-3958 in Firefox
Summary
by MITRE
Use-after-free vulnerability in the nsHTMLEditRules::DeleteNonTableElements 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.
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Analysis
by VulDB Data Team • 10/22/2024
The CVE-2012-3958 vulnerability represents a critical use-after-free flaw within Mozilla Firefox and related applications that fundamentally compromises memory safety mechanisms. This vulnerability exists in the nsHTMLEditRules::DeleteNonTableElements function, which handles HTML editing operations within the browser's rendering engine. The flaw manifests when the application processes certain HTML content that triggers the deletion of non-table elements, creating a scenario where memory previously allocated to an object is accessed after it has been freed, leading to unpredictable behavior and potential exploitation. The vulnerability affects multiple Mozilla products including Firefox versions prior to 15.0, Firefox ESR 10.x versions prior to 10.0.7, Thunderbird versions prior to 15.0, Thunderbird ESR 10.x versions prior to 10.0.7, and SeaMonkey versions prior to 2.12, indicating a widespread impact across the Mozilla ecosystem.
The technical nature of this vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software systems. This flaw operates by manipulating HTML content to trigger a sequence where an object reference is used after the memory containing that object has been deallocated and potentially reallocated for other purposes. When the DeleteNonTableElements function processes malformed HTML input, it creates a scenario where a pointer to freed memory remains accessible, allowing attackers to either execute arbitrary code through heap corruption or induce a denial of service by corrupting heap memory structures. The vulnerability's exploitation requires sophisticated understanding of memory management and browser internals, as attackers must craft specific HTML inputs that will trigger the precise execution path leading to the use-after-free condition.
The operational impact of this vulnerability extends beyond simple exploitation scenarios to encompass both remote code execution and denial of service capabilities, making it particularly dangerous for enterprise and individual users alike. Attackers can leverage this flaw to execute malicious code on vulnerable systems with the privileges of the browser process, potentially leading to complete system compromise. The heap memory corruption aspect means that successful exploitation could result in arbitrary code execution, while less sophisticated attacks might simply cause browser crashes or application instability. The vulnerability's presence across multiple Mozilla products indicates that organizations using these applications face consistent risk exposure regardless of which specific product they employ, creating a significant challenge for security teams managing diverse software environments. This vulnerability particularly affects users who frequently interact with HTML content from untrusted sources, making web browsing and email operations inherently risky.
Mitigation strategies for CVE-2012-3958 should prioritize immediate patch application to all affected versions of Mozilla Firefox, Thunderbird, and SeaMonkey, as this represents the most effective defense against exploitation. Organizations should implement comprehensive patch management processes to ensure all vulnerable systems receive updates promptly, with particular attention to legacy versions that may not receive ongoing support. Network-based mitigations such as content filtering and sandboxing mechanisms can provide additional defense layers, though these should not replace proper patching. Security monitoring should focus on detecting anomalous browser behavior or memory corruption patterns that might indicate exploitation attempts. The vulnerability also underscores the importance of input validation and memory safety practices in web browser development, as highlighted by ATT&CK technique T1059.3, which covers the execution of malicious code through compromised applications. Regular security assessments and vulnerability scanning should include checks for outdated browser versions, while user education about safe browsing practices and email handling remains crucial for reducing attack surface exposure.