CVE-2021-21836 Explained : Impact and Mitigation

A heap-based buffer overflow vulnerability, CVE-2021-21836, has been identified in the GPAC Project on Advanced Content library v1.0.1 due to unchecked arithmetic during MPEG-4 decoding. This could allow an attacker to trigger memory corruption by enticing a user to open a video.

Understanding CVE-2021-21836

This section will provide insights into the nature and impact of CVE-2021-21836, along with technical details, affected systems, and mitigation strategies.

What is CVE-2021-21836?

The vulnerability stems from an integer overflow issue in the MPEG-4 decoding feature of the GPAC Project on Advanced Content library v1.0.1. By leveraging a specially crafted MPEG-4 input with the 'ctts' FOURCC code, an attacker can exploit this flaw to cause a heap-based buffer overflow and induce memory corruption.

The Impact of CVE-2021-21836

With a CVSS base score of 8.8 (High Severity), this vulnerability poses a significant risk to affected systems. An attacker can exploit it over a network without requiring privileges, leading to high impacts on confidentiality, integrity, and availability.

Technical Details of CVE-2021-21836

Understanding the vulnerability description, affected systems, and the mechanism of exploitation is crucial to addressing and preventing CVE-2021-21836.

Vulnerability Description

The flaw arises from an integer overflow to buffer overflow scenario within the MPEG-4 decoding functionality of the GPAC Project on Advanced Content library v1.0.1. Unchecked arithmetic operations allowed for the creation of a specially crafted input that triggers memory corruption.

Affected Systems and Versions

The vulnerability affects GPAC Project Advanced Content commit a8a8d412dabcb129e695c3e7d861fcc81f608304 and GPAC Project Advanced Content v1.0.1 versions.

Exploitation Mechanism

By persuading a user to open a specifically manipulated video, an attacker can exploit the integer overflow vulnerability in the MPEG-4 decoding module, leading to a heap-based buffer overflow and memory corruption.

Mitigation and Prevention

Implementing immediate and long-term security measures, along with applying patches and updates, are essential steps to mitigate the risk posed by CVE-2021-21836.

Immediate Steps to Take

Users are advised to exercise caution when opening video files and ensure that systems are regularly updated with the latest security patches. Consider restricting access to vulnerable components until patches are applied.

Long-Term Security Practices

Employ secure coding practices, conduct regular security assessments, and stay informed about emerging vulnerabilities and best practices to enhance overall system security.

Patching and Updates

Stay informed about official patches released by the vendor to address CVE-2021-21836. Timely application of patches is crucial to fortifying system defenses against potential exploitation.