# CVE-2021-4435: Yarn untrusted search path vulnerability

Source: https://junglewise.ai/threats/cve-2021-4435-yarn-untrusted-search-path-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2024-02-04. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2021-4435 · Severity: low · CVSS 3.1 · Published 2024-02-04

Yarn is a popular package manager for JavaScript projects. An attacker who places malicious content in a directory where a user runs Yarn commands could trick Yarn into executing unintended commands, potentially compromising the user's system and allowing unauthorized access or modification of the project.

Technologies: [yarn (npm)](https://junglewise.ai/threats/technologies/yarn). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2021-4435 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2021-4435 being exploited in the wild.

**How severe is CVE-2021-4435?** Low severity, with a CVSS score of 3.1, published 4 February 2024.

**Which products and versions are affected?** yarn (npm) SEMVER:introduced=0,fixed=1.22.13.

**Is there a fix for CVE-2021-4435?** Yes. yarn (npm): upgrade to 1.22.13 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2021-4435 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2021-4435?** Check whether you run yarn (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- yarn (npm): upgrade to 1.22.13 or later

  ```sh
  npm install yarn@1.22.13
  ```


## Technical details

This is an untrusted search path vulnerability (CWE-426) in Yarn's command execution logic. When Yarn resolves executables, it includes the current working directory in its search path, allowing an attacker to place a malicious script there that gets executed instead of the intended binary. The vulnerability affects all versions before 1.22.13. An attacker must have write access to a directory where a user runs Yarn commands (local attack vector, requires user interaction to run the vulnerable commands). A successful exploit could result in arbitrary code execution with the privileges of the user running Yarn. The fix prevents the current working directory from being a valid resolution path for executable lookups.

## Affected products

- Yarn Yarn all versions before 1.22.13

## Identifiers

- CVE-2021-4435
- GHSA-mpwj-fcr6-x34c

## Timeline

- 2024-02-04: disclosed
- 2024-02-04: patched: Fixed in version 1.22.13

## References

- [https://github.com/yarnpkg/yarn/commit/67fcce88935e45092ffa2674c08053f1ef5268a1](https://github.com/yarnpkg/yarn/commit/67fcce88935e45092ffa2674c08053f1ef5268a1)

## Related threats

- [Yarn package integrity validation TOCTOU race condition](https://junglewise.ai/threats/cve-2019-15608-yarn-package-integrity-validation-toctou-race-condition)
- [Yarn path traversal vulnerability in package installation](https://junglewise.ai/threats/cve-2020-8131-yarn-path-traversal-vulnerability-in-package-installation)
- [Yarn improper link resolution allowing arbitrary symlink creation](https://junglewise.ai/threats/cve-2019-10773-yarn-improper-link-resolution-allowing-arbitrary-symlink-creation)
- [Yarn missing encryption of sensitive data in lockfile](https://junglewise.ai/threats/cve-2019-5448-yarn-missing-encryption-of-sensitive-data-in-lockfile)