# CVE-2021-21861

## Summary

- **CVE ID:** CVE-2021-21861
- **Severity:** HIGH
- **CVSS Score:** 8.8 (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)
- **CWE:** CWE-680
- **Published:** Aug 16, 2021
- **Last Modified:** Mar 13, 2026

## Description

An exploitable integer truncation vulnerability exists within the MPEG-4 decoding functionality of the GPAC Project on Advanced Content library v1.0.1. When processing the 'hdlr' FOURCC code, a specially crafted MPEG-4 input can cause an improper memory allocation resulting in a heap-based buffer overflow that causes memory corruption. An attacker can convince a user to open a video to trigger this vulnerability.

## Affected Products

- n/a — GPAC Project (GPAC Project Advanced Content commit a8a8d412dabcb129e695c3e7d861fcc81f608304, GPAC Project Advanced Content v1.0.1)

## References

- [CNA](https://talosintelligence.com/vulnerability_reports/TALOS-2021-1298)
- [CNA](https://www.debian.org/security/2021/dsa-4966)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.42%
- **EPSS Percentile:** 61.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._