# CVE-2021-23520: Arbitrary File Write via Archive Extraction (Zip Slip)

> Attackers can write arbitrary files outside the intended directory via Zip Slip in the JUCE framework, potentially leading to code execution.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 31 Jan 2022
- **Updated:** 16 Sep 2024
- **Also known as:** DEBIAN-CVE-2021-23520, GHSA-qpj6-xj62-7c95, SNYK-UNMANAGED-JUCEFRAMEWORKJUCE-2388607, UBUNTU-CVE-2021-23520

## What is CVE-2021-23520?

CVE-2021-23520 is a medium-severity path traversal vulnerability in n/a, published on 31 Jan 2022. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

The package juce-framework/juce before 6.1.5 are vulnerable to Arbitrary File Write via Archive Extraction (Zip Slip) via the ZipFile::uncompressEntry function in juce_ZipFile.cpp. This vulnerability is triggered when the archive is extracted upon calling uncompressTo() on a ZipFile object.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2021-23520?

It affects 1 product.


Products: Juce Juce.

## How do I fix CVE-2021-23520?

Upgrade to a fixed version.

## Is CVE-2021-23520 being exploited?

There is no known exploitation of CVE-2021-23520 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-23521](https://insights.sbomify.com/CVE-2021-23521/): Link Following (medium 5.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-23520 and fix it if it is affected.

What it is: CVE-2021-23520 is a medium-severity path traversal vulnerability in n/a, published on 31 Jan 2022. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-23520 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-23520/ (Markdown: https://insights.sbomify.com/CVE-2021-23520/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-23520
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-23520
- OSV: https://osv.dev/vulnerability/CVE-2021-23520

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-23520/
Summaries are generated and may contain mistakes; the official description above is the record.