CVE-2019-11936 Explained : Impact and Mitigation

A vulnerability in HHVM versions prior to 3.30.12 and between 4.0.0 to 4.28.1 allows premature truncation of input due to null bytes in APC functions.

Understanding CVE-2019-11936

What is CVE-2019-11936?

The issue involves premature truncation of input in APC functions that accept keys with null bytes, affecting specific versions of HHVM.

The Impact of CVE-2019-11936

This vulnerability can potentially lead to security breaches and data corruption in systems running the affected HHVM versions.

Technical Details of CVE-2019-11936

Vulnerability Description

The vulnerability arises from the acceptance of keys with null bytes in APC functions, causing premature truncation of input.

Affected Systems and Versions

HHVM versions prior to 3.30.12
HHVM versions between 4.0.0 and 4.8.5
HHVM versions between 4.9.0 and 4.23.1
HHVM versions 4.24.0, 4.25.0, 4.26.0, 4.27.0, 4.28.0, and 4.28.1

Exploitation Mechanism

Attackers can exploit this vulnerability by crafting malicious input with null bytes, leading to unexpected behavior and potential security risks.

Mitigation and Prevention

Immediate Steps to Take

Update HHVM to version 3.30.12 or higher to mitigate the vulnerability
Implement input validation to sanitize user inputs

Long-Term Security Practices

Regularly monitor and audit input handling mechanisms
Conduct security training for developers on secure coding practices

Patching and Updates

Apply patches provided by Facebook for the affected HHVM versions to address the vulnerability