CVE-2020-1921 Explained : Impact and Mitigation

This CVE-2020-1921 article provides insights into a vulnerability affecting HHVM container versions.

Understanding CVE-2020-1921

What is CVE-2020-1921?

The vulnerability in the crypt function of HHVM versions poses a security risk due to improper null termination of a buffer, impacting various version ranges.

The Impact of CVE-2020-1921

The vulnerability affects HHVM versions prior to 4.56.3, versions between 4.57.0 and 4.80.1, versions between 4.81.0 and 4.93.1, and specific versions from 4.94.0 to 4.98.0.

Technical Details of CVE-2020-1921

Vulnerability Description

The issue stems from not validating the buffer offset during null termination, a critical aspect in ensuring secure buffer handling.

Affected Systems and Versions

HHVM versions prior to 4.56.3
HHVM versions between 4.57.0 to 4.80.1
HHVM versions between 4.81.0 to 4.93.1
HHVM versions 4.94.0, 4.95.0, 4.96.0, 4.97.0, 4.98.0

Exploitation Mechanism

Exploitation of this vulnerability can lead to potential stack-based buffer overflow issues and subsequent security breaches.

Mitigation and Prevention

Immediate Steps to Take

Update HHVM to versions that include security patches for CVE-2020-1921
Monitor vendor communications for vulnerability remediation steps

Long-Term Security Practices

Regularly conduct security audits and code reviews to identify similar vulnerabilities
Implement secure coding practices and buffer handling mechanisms

Patching and Updates

Implement available patches or updates provided by Facebook for HHVM to address the CVE-2020-1921 vulnerability.