CVE-2025-14324: CRITICAL JIT Miscompilation Vulnerability in Firefox and Thunderbird | Secably CVE Database

Summary

CVE-2025-14324 is a critical severity vulnerability affecting Mozilla Firefox and Thunderbird. This vulnerability stems from a JIT (Just-In-Time) miscompilation within the JavaScript Engine's JIT component, potentially leading to arbitrary code execution. Immediate patching is strongly recommended.

Technical Details

CVE-2025-14324 describes a Just-In-Time (JIT) miscompilation vulnerability within the JavaScript engine of Firefox and Thunderbird. JIT compilation is a technique used to improve the performance of JavaScript code by compiling it into native machine code during runtime. A miscompilation occurs when the JIT compiler generates incorrect machine code for a given JavaScript program. This can lead to unexpected behavior, including crashes, memory corruption, or, in the worst case, arbitrary code execution. The specific flaw lies within the JIT component, indicating a problem in the code responsible for the dynamic compilation process. An attacker could potentially craft malicious JavaScript code that triggers the miscompilation, allowing them to execute arbitrary code on the victim's machine. The complexity of JIT compilers makes them prone to such vulnerabilities, requiring rigorous testing and security audits.

The root cause of the miscompilation is not publicly available at the time of this writing, but it likely involves a specific sequence of JavaScript operations or data types that expose a flaw in the compiler's logic. Further analysis and reverse engineering of the patched versions of Firefox and Thunderbird would be required to fully understand the underlying mechanism.

Affected Products and Versions

Mozilla Firefox versions prior to 146
Mozilla Firefox ESR versions prior to 115.31
Mozilla Firefox ESR versions prior to 140.6
Mozilla Thunderbird versions prior to 146
Mozilla Thunderbird versions prior to 140.6

Impact Assessment

Successful exploitation of CVE-2025-14324 can lead to arbitrary code execution on the affected system. This means an attacker could potentially gain complete control of the user's machine.

Arbitrary Code Execution: An attacker can execute malicious code on the victim's system with the privileges of the user running Firefox or Thunderbird.
Data Theft: An attacker can steal sensitive data stored on the user's system, including passwords, financial information, and personal documents.
System Compromise: An attacker can install malware, create backdoors, or otherwise compromise the integrity of the user's system.
Denial of Service: The vulnerability could be exploited to crash the application, leading to a denial of service.

Remediation

Immediate Actions

Update Firefox: Upgrade to Firefox version 146 or later.
Update Firefox ESR: Upgrade to Firefox ESR version 115.31 or 140.6 or later.
Update Thunderbird: Upgrade to Thunderbird version 146 or later.
Update Thunderbird: Upgrade to Thunderbird version 140.6 or later.
Verify Update Success: Ensure the update process completes successfully and verify the updated version number.

Long-term Solutions

Enable Automatic Updates: Configure Firefox and Thunderbird to automatically install security updates to minimize the window of vulnerability.
Security Awareness Training: Educate users about the risks of visiting untrusted websites and opening suspicious attachments.

References

Detection & Scanning

Organizations can detect vulnerable versions of Firefox and Thunderbird by using vulnerability scanners that identify software versions. Regular security audits and penetration testing can also help identify potential exploitation vectors.

Scan Your Website

Secably AI Scanner can detect this and 50+ other vulnerabilities automatically.

Start Free Scan