CVE-2026-26021

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.

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