CVE-2021-21861
CVSS v3
8.8
HIGH
EPSS Score
1.6 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
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.
Technical details
- Published
- 2021-08-16
Frequently asked questions
What is CVE-2021-21861?
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.
Is CVE-2021-21861 actively exploited?
Active exploitation of CVE-2021-21861 has not been confirmed. Its EPSS score was 1.6% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2021-21861?
CVE-2021-21861 has a CVSS v3 base score of 8.8 (HIGH severity).
Is CVE-2021-21861 affecting your environment?
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