What is CVE-2020-18776?

CVE-2020-18776 is a medium-severity vulnerability in Libav, classified under Out-of-bounds Read. CVSS score: 6.5/10. Published 2021-08-23.

How severe is CVE-2020-18776?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Out-of-bounds Read in Libav

CVE-2020-18776

In Libav 12.3, there is a segmentation fault in vc1_decode_b_mb_intfr in vc1_block.c that allows an attacker to cause denial-of-service via a crafted file.

Vulnerability class: Buffer Overflow

Published 2021-08-23 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.009 (57.4th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 57th percentile — 57.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Libav — versions 12.3

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

References

bugzilla.libav.org/show_bug.cgi (Exploit, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2020-18776?: CVE-2020-18776 is a medium-severity vulnerability in Libav, classified under Out-of-bounds Read. CVSS score: 6.5/10. Published 2021-08-23.
How severe is CVE-2020-18776?: Medium severity. CVSS v3 base score is 6.5 out of 10.