CVE-2019-9791 Explained : Impact and Mitigation

A vulnerability in Mozilla products could allow unauthorized access and modification of objects, potentially leading to exploitable crashes.

Understanding CVE-2019-9791

This CVE affects Thunderbird, Firefox ESR, and Firefox versions due to type confusions between objects compiled using the IonMonkey JIT compiler.

What is CVE-2019-9791?

The vulnerability arises from incorrect type inference for constructors entered via on-stack replacement with IonMonkey, allowing unauthorized access and modification of objects.

The Impact of CVE-2019-9791

The vulnerability could result in unauthorized access and modification of objects, potentially leading to exploitable crashes.

Technical Details of CVE-2019-9791

The vulnerability description, affected systems, and exploitation mechanism are detailed below.

Vulnerability Description

The type inference system enables functions to be compiled using the IonMonkey JIT compiler, leading to type confusions between objects, specifically when constructor functions are entered via on-stack replacement (OSR).

Affected Systems and Versions

Thunderbird versions prior to 60.6
Firefox ESR versions prior to 60.6
Firefox versions prior to 66

Exploitation Mechanism

Type confusions between objects
Unauthorized access and modification of objects
Potential exploitable crashes

Mitigation and Prevention

Steps to mitigate and prevent exploitation of CVE-2019-9791 are crucial.

Immediate Steps to Take

Update Thunderbird, Firefox ESR, and Firefox to versions 60.6 and 66, respectively
Monitor for any unauthorized access or modifications

Long-Term Security Practices

Regularly update Mozilla products to the latest versions
Implement secure coding practices to prevent type confusions

Patching and Updates

Apply patches provided by Mozilla to address the vulnerability