CVE-2011-3659 in Firefox
Summary
by MITRE
Use-after-free vulnerability in Mozilla Firefox before 3.6.26 and 4.x through 9.0, Thunderbird before 3.1.18 and 5.0 through 9.0, and SeaMonkey before 2.7 might allow remote attackers to execute arbitrary code via vectors related to incorrect AttributeChildRemoved notifications that affect access to removed nsDOMAttribute child nodes.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 06/09/2025
The CVE-2011-3659 vulnerability represents a critical use-after-free flaw affecting multiple Mozilla products including Firefox, Thunderbird, and SeaMonkey. This vulnerability stems from improper handling of AttributeChildRemoved notifications within the browser engine's DOM (Document Object Model) processing mechanisms. The flaw occurs when the system attempts to access memory locations that have already been freed, creating a scenario where malicious code can potentially execute arbitrary commands on affected systems. The vulnerability affects specific version ranges including Firefox versions prior to 3.6.26 and 4.x through 9.0, Thunderbird versions before 3.1.18 and 5.0 through 9.0, and SeaMonkey versions before 2.7.
The technical root cause of this vulnerability lies in the incorrect processing of DOM attribute notifications within the Mozilla rendering engine. When DOM attributes are removed from the document structure, the system should properly invalidate references to those attributes and prevent further access to their memory locations. However, in affected versions, the AttributeChildRemoved notification mechanism fails to properly manage the lifecycle of nsDOMAttribute child nodes, leading to situations where freed memory can still be accessed. This improper memory management creates a use-after-free condition that can be exploited by remote attackers. The vulnerability specifically impacts the interaction between the DOM tree manipulation code and the notification system that should alert components when attribute changes occur, but fails to properly synchronize these operations.
The operational impact of this vulnerability is severe and can be exploited remotely by attackers to achieve arbitrary code execution on vulnerable systems. Attackers can craft malicious web pages or email content that, when processed by the affected browser or email client, triggers the flawed notification handling mechanism. This exploitation can lead to complete system compromise, allowing attackers to execute malicious code with the privileges of the affected application. The vulnerability is particularly dangerous because it can be triggered through standard web browsing or email processing activities, making it an attractive target for phishing campaigns and drive-by download attacks. The use-after-free condition provides attackers with a reliable mechanism for memory corruption that can be leveraged to bypass modern exploit mitigations such as ASLR and DEP.
Security professionals should implement immediate mitigation strategies including prompt patching of all affected versions, deployment of web application firewalls, and network segmentation to limit exposure. The vulnerability aligns with CWE-416 which describes use-after-free conditions, and represents a classic example of memory safety issues that can be addressed through proper memory management practices. From an ATT&CK framework perspective, this vulnerability maps to T1059 for command and script injection and T1190 for exploitation of remote services, demonstrating how a single memory corruption flaw can enable multiple attack vectors. Organizations should prioritize updating to patched versions of Mozilla products and consider implementing additional security controls such as sandboxing and exploit prevention mechanisms to reduce the risk of successful exploitation. The vulnerability also highlights the importance of proper memory management in complex software systems and serves as a reminder of the critical need for thorough testing of DOM manipulation and notification handling code paths.