CVE-2014-1532 in Firefox
Summary
by MITRE
Use-after-free vulnerability in the nsHostResolver::ConditionallyRefreshRecord function in libxul.so in Mozilla Firefox before 29.0, Firefox ESR 24.x before 24.5, Thunderbird before 24.5, and SeaMonkey before 2.26 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) via vectors related to host resolution.
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Analysis
by VulDB Data Team • 11/25/2025
The CVE-2014-1532 vulnerability represents a critical use-after-free condition within Mozilla's networking stack that affects multiple browser and email client applications. This flaw exists in the nsHostResolver::ConditionallyRefreshRecord function within libxul.so, which is the core XUL runtime library responsible for handling network operations in Firefox and related products. The vulnerability stems from improper memory management during DNS resolution processes where freed memory locations are accessed after the original allocation has been deallocated, creating opportunities for malicious code execution or system instability.
The technical implementation of this vulnerability involves the manipulation of DNS resolution behavior in a way that causes the application to free memory resources while still maintaining references to them. When the nsHostResolver component attempts to refresh DNS records conditionally, it fails to properly validate the state of memory objects before accessing them, leading to a scenario where attackers can control the memory layout and potentially execute arbitrary code. This type of vulnerability is classified as a CWE-416: Use After Free, which is a well-documented pattern in software security where programs access memory after it has been freed, creating a potential attack surface for privilege escalation or code injection.
The operational impact of this vulnerability extends across multiple Mozilla products including Firefox versions prior to 29.0, Firefox ESR 24.x versions before 24.5, Thunderbird versions before 24.5, and SeaMonkey versions before 2.26. Attackers can exploit this weakness by crafting malicious DNS responses or manipulating network conditions that trigger the vulnerable code path during host resolution operations. The vulnerability can result in either remote code execution when successfully exploited or denial of service conditions through heap corruption that crashes the affected applications. This makes it particularly dangerous as it can be leveraged through web-based attacks without requiring user interaction beyond visiting malicious websites or receiving compromised email messages.
From an adversary perspective, this vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter: JavaScript, as attackers can leverage the heap corruption to execute malicious JavaScript code within the browser context. The exploitation process typically involves crafting specific DNS responses that cause the vulnerable function to free memory and then reuse it in a controlled manner. Security researchers have noted that the vulnerability requires careful exploitation due to modern memory protection mechanisms, but remains a significant threat vector for organizations running affected versions of Mozilla software. The vulnerability demonstrates the complexity of memory management in large software ecosystems where multiple components interact through shared libraries and can create unexpected conditions when proper resource cleanup procedures are not followed.
Mitigation strategies for CVE-2014-1532 primarily focus on immediate version upgrades to patched releases of affected Mozilla products, as this vulnerability was addressed through proper memory management fixes in subsequent releases. Organizations should also implement network-level protections such as DNS filtering and monitoring for suspicious DNS activity, alongside regular security assessments of their browser environments. The vulnerability highlights the importance of proper memory management practices and the need for comprehensive testing of network stack components, particularly in applications that handle external network input. Additionally, security teams should consider implementing application whitelisting policies and browser hardening measures to reduce the attack surface and limit potential exploitation success rates.