CVE-2018-12292 in Pale Moon
Summary
by MITRE
A use-after-free vulnerability exists in DOMProxyHandler::EnsureExpandoObject in Pale Moon before 27.9.3.
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Analysis
by VulDB Data Team • 10/14/2025
The vulnerability identified as CVE-2018-12292 represents a critical use-after-free condition within the DOMProxyHandler::EnsureExpandoObject function of the Pale Moon web browser. This flaw resides in the browser's handling of JavaScript proxy objects and their associated expandable properties, creating a scenario where memory that has been freed is still accessed by subsequent operations. The vulnerability affects Pale Moon versions prior to 27.9.3, indicating that it was present in the browser's JavaScript engine implementation for an extended period. The issue stems from improper memory management during proxy object operations where the browser fails to properly track object lifetimes and reference counts, leading to scenarios where freed memory regions are reused or accessed beyond their intended lifecycle.
The technical nature of this vulnerability places it squarely within the category of memory safety issues, specifically classified under CWE-416 as use-after-free conditions. This type of vulnerability occurs when a program continues to reference memory after it has been freed, potentially allowing attackers to execute arbitrary code or cause unexpected behavior. In the context of web browsers, such vulnerabilities are particularly dangerous because they can be exploited through malicious web content, making them ideal targets for remote code execution attacks. The DOMProxyHandler::EnsureExpandoObject function serves as a critical component in the browser's JavaScript engine, managing how proxy objects interact with their underlying data structures and expandable properties.
The operational impact of CVE-2018-12292 extends beyond simple browser instability, as it creates potential attack vectors that could be exploited by malicious actors. When an attacker crafts specific JavaScript code that triggers the vulnerable code path, they can manipulate the browser's memory management to cause the use-after-free condition. This could result in the execution of arbitrary code with the privileges of the browser process, potentially leading to full system compromise. The vulnerability demonstrates how complex JavaScript engine components can introduce security risks when proper memory management practices are not followed, particularly in scenarios involving proxy objects and their dynamic property handling. Attackers could leverage this vulnerability through various attack vectors including malicious websites, phishing campaigns, or drive-by downloads that specifically target the affected browser versions.
Mitigation strategies for CVE-2018-12292 primarily involve upgrading to Pale Moon version 27.9.3 or later, which contains the necessary patches to address the memory management issues in the DOMProxyHandler::EnsureExpandoObject function. Security administrators should prioritize this update across all affected systems, particularly in enterprise environments where browser security is paramount. Additionally, implementing content security policies, disabling unnecessary JavaScript features, and maintaining strict browser security configurations can provide additional defense-in-depth measures. The vulnerability highlights the importance of regular security updates and the need for comprehensive testing of browser components, especially those handling complex memory management scenarios. Organizations should also consider implementing monitoring solutions to detect potential exploitation attempts and maintain awareness of similar vulnerabilities in other browser engines that may present comparable risks through their proxy object implementations. This vulnerability serves as a reminder of the critical importance of proper memory management in browser security and the potential consequences of inadequate safeguards in JavaScript engine components that handle dynamic object manipulation.