CVE-2021-38171

Name: CVE-2021-38171
Creator: NVD / NIST
Published: 2021-08-21T17:15:07.7+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 2.41%

Last modified Jun 17, 2026

CVE-2021-38171 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. adts_decode_extradata in libavformat/adtsenc.c in FFmpeg 4.4 does not check the init_get_bits return value, which is a necessary step because the second argument to init_get_bits can be crafted.. EPSS estimates a 2.41% chance of exploitation in the next 30 days.

Description

adts_decode_extradata in libavformat/adtsenc.c in FFmpeg 4.4 does not check the init_get_bits return value, which is a necessary step because the second argument to init_get_bits can be crafted.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

2.41%

82.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-252

Affected Software

Vendor	Product	Versions
Ffmpeg	Ffmpeg	4.4
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0
Debian	Debian Linux	11.0

References

https://github.com/FFmpeg/FFmpeg/commit/9ffa49496d1aae4cbbb387aac28a9e061a6ab0a6Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/11/msg00012.htmlMailing List, Third Party Advisory
https://patchwork.ffmpeg.org/project/ffmpeg/patch/AS8P193MB12542A86E22F8207EC971930B6F19%40AS8P193MB1254.EURP193.PROD.OUTLOOK.COM/
https://security.gentoo.org/glsa/202312-14
https://www.debian.org/security/2021/dsa-4990Third Party Advisory
https://www.debian.org/security/2021/dsa-4998Third Party Advisory
https://github.com/FFmpeg/FFmpeg/commit/9ffa49496d1aae4cbbb387aac28a9e061a6ab0a6Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/11/msg00012.htmlMailing List, Third Party Advisory
https://patchwork.ffmpeg.org/project/ffmpeg/patch/AS8P193MB12542A86E22F8207EC971930B6F19%40AS8P193MB1254.EURP193.PROD.OUTLOOK.COM/
https://security.gentoo.org/glsa/202312-14
https://www.debian.org/security/2021/dsa-4990Third Party Advisory
https://www.debian.org/security/2021/dsa-4998Third Party Advisory

Timeline

Published: Aug 21, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-38171?

adts_decode_extradata in libavformat/adtsenc.c in FFmpeg 4.4 does not check the init_get_bits return value, which is a necessary step because the second argument to init_get_bits can be crafted.

How severe is CVE-2021-38171?

CVE-2021-38171 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 2.41% probability of exploitation in the next 30 days.

How do I fix CVE-2021-38171?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-38171?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST