# CVE-2026-26021

## Summary

- **CVE ID:** CVE-2026-26021
- **Severity:** CRITICAL
- **CVSS Score:** 9.4 (CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H)
- **CWE:** CWE-1321
- **Published:** Feb 11, 2026
- **Last Modified:** Mar 12, 2026

## Description

set-in provides the set value of nested associative structure given array of keys. A prototype pollution vulnerability exists in the the npm package set-in (>=2.0.1, < 2.0.5). Despite a previous fix that attempted to mitigate prototype pollution by checking whether user input contained a forbidden key, it is still possible to pollute Object.prototype via a crafted input using Array.prototype. This has been fixed in version 2.0.5.

## Affected Products

- ahdinosaur — set-in (>= 2.0.1, < 2.0.5)

## References

- [CNA](https://github.com/ahdinosaur/set-in/security/advisories/GHSA-2c4m-g7rx-63q7)
- [CNA](https://github.com/ahdinosaur/set-in/commit/b8e1dabfdbd35c8d604b6324e01d03f280256c3d)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.46%
- **EPSS Percentile:** 38.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._