CVE-2024-29944 in Firefox
Summary
by MITRE • 03/22/2024
An attacker was able to inject an event handler into a privileged object that would allow arbitrary JavaScript execution in the parent process. This vulnerability affects Firefox < 124.0.1 and Firefox ESR < 115.9.1.
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Analysis
by VulDB Data Team • 06/18/2025
This vulnerability represents a critical privilege escalation flaw in Mozilla Firefox browsers that allows remote attackers to execute arbitrary JavaScript code within the parent process context. The issue stems from insufficient input validation and sanitization mechanisms that permit malicious event handler injection into privileged objects. Attackers can leverage this weakness to bypass security boundaries that typically isolate untrusted content from privileged browser processes, effectively breaking down the security model that separates user-facing interfaces from core browser functionality.
The technical implementation of this vulnerability involves the exploitation of improper event handling mechanisms within Firefox's security architecture. When a privileged object receives unvalidated event data, the browser fails to properly sanitize the input before attaching it as an event handler. This creates a scenario where malicious JavaScript code can be injected into trusted execution contexts, allowing attackers to execute arbitrary code with the privileges of the parent browser process. The flaw specifically impacts Firefox versions prior to 124.0.1 and Firefox ESR versions prior to 115.9.1, indicating that these releases contained inadequate security controls around event handler attachment and execution.
The operational impact of this vulnerability extends beyond simple code execution, as it fundamentally undermines the browser's security sandboxing mechanisms. An attacker who successfully exploits this vulnerability can potentially access sensitive user data, manipulate browser functionality, and perform actions that would normally be restricted to privileged processes. This includes accessing local files, modifying browser settings, and potentially establishing persistent access to the victim's system. The vulnerability affects the core security model of Firefox, which relies on strict isolation between different privilege levels within the browser architecture.
From a cybersecurity perspective, this vulnerability aligns with CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')" and maps to ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript." The flaw demonstrates how improper input validation can lead to privilege escalation, making it particularly dangerous for web-based attacks. Organizations should prioritize immediate patching of affected Firefox versions to prevent exploitation, as the vulnerability can be leveraged through malicious websites or compromised web content without requiring user interaction beyond visiting the compromised site.
Mitigation strategies should include immediate deployment of security patches to Firefox versions 124.0.1 and 115.9.1 respectively, along with monitoring for suspicious browser behavior that might indicate exploitation attempts. Network security controls such as web application firewalls and content filtering systems can provide additional protection layers, though they may not prevent this specific attack vector. Browser hardening measures including disabling unnecessary JavaScript features and implementing strict content security policies can reduce the attack surface, while user education about visiting only trusted websites remains essential for comprehensive protection against such vulnerabilities.