How severe is CVE-2021-30123?

CVE-2021-30123 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-30123 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-30123?

CVE-2021-30123 affects Ffmpeg. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-30123?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-30123 published?

CVE-2021-30123 was published on 2021-04-07 and last updated on 2026-06-17.

CVE-2021-30123

Q: What is CVE-2021-30123?

FFmpeg <=4.3 contains a buffer overflow vulnerability in libavcodec through a crafted file that may lead to remote code execution.

CVE-2021-30123 is a high-severity vulnerability in Ffmpeg with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-120.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.8
EPSS exploit prediction: 3% (87th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Ffmpeg
Published: 2021-04-07
Last modified: 2026-06-17

Description

FFmpeg <=4.3 contains a buffer overflow vulnerability in libavcodec through a crafted file that may lead to remote code execution.

Frequently asked questions

What is CVE-2021-30123?: FFmpeg <=4.3 contains a buffer overflow vulnerability in libavcodec through a crafted file that may lead to remote code execution.
How severe is CVE-2021-30123?: CVE-2021-30123 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-30123 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (87th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-30123?: CVE-2021-30123 affects Ffmpeg. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-30123?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-30123 published?: CVE-2021-30123 was published on 2021-04-07 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:ffmpeg:ffmpeg:4.4:*:*:*:*:*:*:*

More vulnerabilities in Ffmpeg

CVE-2013-0864 — Critical (CVSS 10.0): The gif_copy_img_rect function in libavcodec/gifdec.c in FFmpeg before 1.1.2 performs an incorrect calculation for an…
CVE-2013-4265 — Critical (CVSS 10.0): The av_reallocp_array function in libavutil/mem.c in FFmpeg before 2.0.1 has an unspecified impact and remote vectors…
CVE-2013-0873 — Critical (CVSS 10.0): The read_header function in libavcodec/shorten.c in FFmpeg before 1.1.3 allows remote attackers to have an unspecified…
CVE-2013-0872 — Critical (CVSS 10.0): The swr_init function in libswresample/swresample.c in FFmpeg before 1.1.3 allows remote attackers to have an…
CVE-2011-3937 — Critical (CVSS 10.0): The H.263 codec (libavcodec/h263dec.c) in FFmpeg 0.7.x before 0.7.12, 0.8.x before 0.8.11, and unspecified versions…
CVE-2012-2804 — Critical (CVSS 10.0): Unspecified vulnerability in libavcodec/indeo3.c in FFmpeg before 0.11 and Libav 0.8.x before 0.8.5 has unknown impact…

All CVEs affecting Ffmpeg →

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