What is CVE-2019-9720?

CVE-2019-9720 is a medium-severity vulnerability in Libav, classified under Out-of-bounds Write. CVSS score: 6.5/10. Published 2019-09-19.

How severe is CVE-2019-9720?

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

Buffer overflow in Libav

CVE-2019-9720

A stack-based buffer overflow in the subtitle decoder in Libav 12.3 allows attackers to corrupt the stack via a crafted video file in Matroska format, because srt_to_ass in libavcodec/srtdec.c misuses snprintf.

Vulnerability class: Buffer Overflow

Published 2019-09-19 · 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: 0.011 (64.1th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 64th percentile — 64.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: 0.000

Affected products

Libav

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

github.com/libav/libav/blob/df744e3cf66548c9167ea857104a29d2ea92819e/libavcodec… (Exploit, Third Party Advisory)
lgtm.com/security/ (Third Party Advisory)

Frequently asked questions

What is CVE-2019-9720?: CVE-2019-9720 is a medium-severity vulnerability in Libav, classified under Out-of-bounds Write. CVSS score: 6.5/10. Published 2019-09-19.
How severe is CVE-2019-9720?: Medium severity. CVSS v3 base score is 6.5 out of 10.