# CVE-2020-8131: Path Traversal in Yarn

> Attackers can write to arbitrary filesystem paths via malicious packages, potentially leading to code execution in Yarn.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 24 Feb 2020
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2020-8131, GHSA-8mfc-v7wv-p62g, ROOT-APP-NPM-CVE-2020-8131

## What is CVE-2020-8131?

CVE-2020-8131 is a high-severity path traversal vulnerability in yarn, published on 24 Feb 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Arbitrary filesystem write vulnerability in Yarn before 1.22.0 allows attackers to write to any path on the filesystem and potentially lead to arbitrary code execution by forcing the user to install a malicious package.

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

## Which versions are affected by CVE-2020-8131?

2 open source packages ship an affected version, including yarn. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `yarn` | npm | All versions | 1.22.0 |
| `yarn` | npm | All versions | 1.22.0 |

Products: Yarnpkg Yarn.

## How do I fix CVE-2020-8131?

Upgrade yarn to 1.22.0 or later.

## Is CVE-2020-8131 being exploited?

There is no known exploitation of CVE-2020-8131 in the wild and no public exploit code.

## Other vulnerabilities in yarn

- [CVE-2019-5448](https://insights.sbomify.com/CVE-2019-5448/): Missing Encryption of Sensitive Data in yarn (high 8.1)
- [CVE-2019-10773](https://insights.sbomify.com/CVE-2019-10773/): Yarn Improper link resolution before file access (Link Following) (high 7.8)
- [CVE-2021-4435](https://insights.sbomify.com/CVE-2021-4435/): Yarn: untrusted search path (high 7.7)
- [CVE-2019-15608](https://insights.sbomify.com/CVE-2019-15608/): TOCTOU Race Condition in Yarn (medium 5.9)
- [CVE-2025-8262](https://insights.sbomify.com/CVE-2025-8262/): yarnpkg Yarn hosted-git-resolver.js explodeHostedGitFragment redos (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-8131 and fix it if it is affected.

What it is: CVE-2020-8131 is a high-severity path traversal vulnerability in yarn, published on 24 Feb 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-8131 in the wild and no public exploit code.

Affected packages and fixed versions:
- yarn (npm): affected all versions; fixed in 1.22.0
- yarn (npm): affected all versions; fixed in 1.22.0

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-2020-8131/ (Markdown: https://insights.sbomify.com/CVE-2020-8131/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-8131
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-8131
- OSV: https://osv.dev/vulnerability/CVE-2020-8131

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-8131/
Summaries are generated and may contain mistakes; the official description above is the record.