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Vulnerability record · CVE-2019-9720 · published 19 September 2019

CVE-2019-9720: Libav out-of-bounds write vulnerability

Libav · Libav

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.

6.5 CVSS 3.1 Medium EPSS 1.1% · top 35.8% CWE-787 · Out-of-bounds write
6.5CVSS 3.1 base score, v2 7.1
1.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/libav/libav/blob/df744e3cf66548c9167ea857104a29d2ea92819e/libavcodec/srtdec.c#L161 ExploitThird Party Advisory
https://lgtm.com/security/ Third Party Advisory
https://github.com/libav/libav/blob/df744e3cf66548c9167ea857104a29d2ea92819e/libavcodec/srtdec.c#L161 ExploitThird Party Advisory
https://lgtm.com/security/ Third Party Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2019-9720), CISA KEV, FIRST EPSS (scores of 2026-10-02). This page is refreshed as NVD updates the record.