CVE-2021-21849 : Exploit Details and Defense Strategies

An exploitable integer overflow vulnerability exists within the MPEG-4 decoding functionality of the GPAC Project on Advanced Content library v1.0.1, allowing an attacker to trigger a heap-based buffer overflow and memory corruption. This article provides insights into the impact, technical details, and mitigation strategies for CVE-2021-21849.

Understanding CVE-2021-21849

This section delves into the details of the CVE-2021-21849 vulnerability.

What is CVE-2021-21849?

CVE-2021-21849 is an integer overflow vulnerability present in the GPAC Project's Advanced Content library v1.0.1, triggered by specially crafted MPEG-4 input. It leads to memory corruption via a heap-based buffer overflow.

The Impact of CVE-2021-21849

With a CVSS base score of 8.8 (High severity), this vulnerability poses a significant threat. Attackers can exploit it to execute arbitrary code or crash the application, potentially compromising confidentiality, integrity, and availability.

Technical Details of CVE-2021-21849

This section outlines the technical aspects of CVE-2021-21849.

Vulnerability Description

The vulnerability arises from unchecked arithmetic in handling MPEG-4 atoms with the "tfra" FOURCC code, resulting in an integer overflow. This triggers a heap-based buffer overflow when processing video content.

Affected Systems and Versions

GPAC Project Advanced Content commit a8a8d412dabcb129e695c3e7d861fcc81f608304 and v1.0.1 are affected by this vulnerability.

Exploitation Mechanism

Attackers can exploit CVE-2021-21849 by crafting malicious MPEG-4 content and enticing users to open a video, thereby triggering the integer overflow and subsequent memory corruption.

Mitigation and Prevention

This section provides guidance on addressing CVE-2021-21849.

Immediate Steps to Take

Users and organizations should apply security patches promptly, restrict access to vulnerable systems, and exercise caution when interacting with untrusted video files.

Long-Term Security Practices

Implement robust security measures such as input validation, secure coding practices, and regular security audits to mitigate the risk of similar vulnerabilities.

Patching and Updates

Stay informed about security advisories from GPAC Project and related vendors to apply patches as soon as they are released.