CVE-2013-5616 in Firefox
Summary
by MITRE
Use-after-free vulnerability in the nsEventListenerManager::HandleEventSubType function in Mozilla Firefox before 26.0, Firefox ESR 24.x before 24.2, Thunderbird before 24.2, and SeaMonkey before 2.23 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) via vectors related to mListeners event listeners.
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Analysis
by VulDB Data Team • 11/25/2025
The CVE-2013-5616 vulnerability represents a critical use-after-free flaw within Mozilla Firefox's event handling subsystem that existed across multiple products including Firefox, Firefox ESR, Thunderbird, and SeaMonkey. This vulnerability specifically targets the nsEventListenerManager::HandleEventSubType function which manages how event listeners are processed within the browser's rendering engine. The flaw occurs when the browser processes event listeners that have been previously destroyed but are still being referenced, creating a scenario where memory that has been freed is accessed again, leading to unpredictable behavior and potential exploitation.
The technical nature of this vulnerability stems from improper memory management within the browser's event listener architecture. When event listeners are removed from the mListeners collection, the associated memory may not be properly invalidated or cleared, allowing subsequent event processing to reference freed memory locations. This creates a classic use-after-free condition that can be exploited by attackers to manipulate heap memory layout and potentially execute arbitrary code. The vulnerability manifests during event handling operations where the browser attempts to process events that reference destroyed listener objects, causing heap corruption that can be leveraged for privilege escalation or denial of service attacks.
From an operational perspective, this vulnerability presents significant risks to users of affected browser versions as it enables remote code execution without requiring user interaction beyond visiting a malicious website or opening a specially crafted email message. Attackers can craft web content or email attachments that trigger the vulnerable code path, leading to heap corruption that may allow them to execute malicious code with the privileges of the browser process. The impact extends beyond simple exploitation as the vulnerability can also cause denial of service conditions that disrupt normal browser operation, potentially leading to system instability or complete browser crashes that require manual intervention to resolve.
The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software systems, and demonstrates how improper memory management can create persistent security risks in complex applications. From an attacker's perspective, this vulnerability maps to several ATT&CK techniques including TA0002 (Execution) and TA0005 (Defense Evasion) as it provides a method for executing arbitrary code and potentially bypassing security controls. The attack surface is particularly concerning given that the vulnerability affects multiple Mozilla products and can be triggered through standard web browsing or email processing activities, making it a high-priority target for threat actors seeking to compromise user systems.
Organizations should prioritize immediate patching of all affected versions to mitigate this vulnerability, as the window for exploitation remains open for systems running unsupported versions of these browsers. Security teams should implement network monitoring to detect potential exploitation attempts and consider deploying browser hardening measures such as sandboxing and memory protection features that can limit the impact of such vulnerabilities even if they are not immediately patched. Additionally, user education regarding the importance of keeping browser software updated and avoiding untrusted web content remains critical in defending against exploitation attempts that leverage this type of memory corruption vulnerability.