CVE-2024-3852: Mozilla Firefox Use-After-Free Vulnerability

CVE-2024-3852 Overview

CVE-2024-3852 is a Type Confusion vulnerability affecting Mozilla Firefox and Thunderbird applications. The vulnerability exists in the GetBoundName function, which can return an incorrect version of an object when Just-In-Time (JIT) compiler optimizations are applied. This flaw could potentially allow attackers to manipulate object states in unexpected ways, leading to security issues in the JavaScript engine.

Critical Impact

Exploitation of this vulnerability through malicious web content could allow attackers to achieve high impact on confidentiality, integrity, and availability of affected systems through incorrect object version handling during JIT compilation.

Affected Products

• Mozilla Firefox versions prior to 125
• Mozilla Firefox ESR versions prior to 115.10
• Mozilla Thunderbird versions prior to 115.10

Discovery Timeline

• April 16, 2024 - CVE-2024-3852 published to NVD
• April 1, 2025 - Last updated in NVD database

Technical Details for CVE-2024-3852

Vulnerability Analysis

The vulnerability resides in Mozilla's JavaScript engine, specifically within the GetBoundName function. When JIT optimizations are enabled, this function may incorrectly return a stale or wrong version of an object. JIT compilers optimize JavaScript execution by compiling frequently executed code paths into native machine code, but this optimization process can introduce subtle bugs when object state tracking becomes desynchronized.

The core issue relates to CWE-386 (Symbolic Name not Mapping to Correct Object), indicating that the internal symbolic reference mechanism fails to correctly map to the intended object version after JIT transformations have been applied. This class of vulnerability can lead to type confusion scenarios where the engine operates on an object with incorrect assumptions about its current state or type.

The network-based attack vector requires user interaction, as exploitation would typically occur through a user visiting a malicious webpage or viewing malicious content in an email client (Thunderbird). The high attack complexity reflects the difficulty in reliably triggering the JIT optimization path necessary for exploitation.

Root Cause

The root cause is a synchronization issue between the JIT compiler's optimization passes and the GetBoundName function's object resolution logic. When the JIT compiler optimizes code paths, it makes assumptions about object states that may become invalid, causing GetBoundName to return references to outdated or incorrect object versions. This creates a desynchronization between what the optimized code expects and what actually exists in memory.

Attack Vector

An attacker could exploit this vulnerability by crafting malicious JavaScript code designed to trigger specific JIT optimization paths. The attack would typically be delivered via:

1. A malicious website visited by the victim using a vulnerable Firefox browser
2. A malicious email containing HTML/JavaScript content viewed in Thunderbird
3. Specially crafted web content embedded in trusted sites through advertising or other injection vectors

The vulnerability manifests when the JIT compiler optimizes code that subsequently calls GetBoundName under specific conditions that cause object version misalignment. Detailed technical analysis is available in the Mozilla Bug Report #1883542. Due to the complexity of JIT-related vulnerabilities, successful exploitation requires precise timing and understanding of the compiler's optimization behavior.

Detection Methods for CVE-2024-3852

Indicators of Compromise

• Unusual JavaScript execution patterns in browser logs indicating potential JIT manipulation
• Unexpected browser crashes or memory corruption events in Firefox or Thunderbird
• Anomalous network requests following suspicious JavaScript execution
• Evidence of exploitation attempts in web server logs showing delivery of obfuscated JavaScript

Detection Strategies

• Monitor for Firefox/Thunderbird versions prior to the patched releases (125, 115.10 ESR, 115.10 respectively) in endpoint inventory
• Implement browser version compliance checks using endpoint detection and response (EDR) solutions
• Deploy web filtering rules to detect known malicious JavaScript patterns targeting JIT vulnerabilities
• Enable enhanced telemetry and crash reporting to identify potential exploitation attempts

Monitoring Recommendations

• Configure SentinelOne agents to alert on outdated Mozilla product versions across the enterprise
• Implement network monitoring for suspicious JavaScript payload delivery to endpoint browsers
• Enable browser crash dump collection and analysis for potential exploitation indicators
• Monitor for unexpected child process spawning from Firefox or Thunderbird processes

How to Mitigate CVE-2024-3852

Immediate Actions Required

• Update Mozilla Firefox to version 125 or later immediately
• Update Mozilla Firefox ESR to version 115.10 or later
• Update Mozilla Thunderbird to version 115.10 or later
• Consider temporarily disabling JIT compilation as an interim measure if immediate patching is not possible

Patch Information

Mozilla has released security patches addressing this vulnerability across multiple product lines. Organizations should apply the relevant updates based on their deployment:

• Firefox: Update to version 125 or later - Mozilla Security Advisory MFSA-2024-18
• Firefox ESR: Update to version 115.10 or later - Mozilla Security Advisory MFSA-2024-19
• Thunderbird: Update to version 115.10 or later - Mozilla Security Advisory MFSA-2024-20

Debian-based systems should also reference the Debian LTS Announcement #12 and Debian LTS Announcement #13 for distribution-specific patches.

Workarounds

• Disable JIT compilation by setting javascript.options.ion to false in about:config (Firefox) as a temporary mitigation
• Implement strict content security policies to limit JavaScript execution from untrusted sources
• Use browser isolation technologies to contain potential exploitation attempts
• Block access to known malicious domains that may attempt to exploit this vulnerability

# Firefox/Thunderbird JIT disable workaround (user.js or policies)
# Add to user.js in Firefox profile directory
user_pref("javascript.options.ion", false);
user_pref("javascript.options.baselinejit", false);
user_pref("javascript.options.native_regexp", false);