What’s Vulnerable › Vulnerabilities

CVE-2026-26021: Prototype pollution in set-in

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-02-11 · updated 2026-06-17
• Weakness: CWE-1321

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

• set-in: from 2.0.1 before 2.0.5 — fixed in 2.0.5

How to fix

Upgrade to a fixed version: set-in 2.0.5. Check the vendor advisory for mitigations.

References

• https://github.com/ahdinosaur/set-in/commit/b8e1dabfdbd35c8d604b6324e01d03f280256c3d
• https://github.com/ahdinosaur/set-in/security/advisories/GHSA-2c4m-g7rx-63q7

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