CVE-2026-26021CWE-1321

Prototype pollution in set-in

Critical · published February 11, 2026

CVSS v4.0
9.4
EPSS
1%
Percentile
46.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
9.4 · CRITICAL
Vector
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
EPSS
0.00562 · 46.0th percentile
Weakness
CWE-1321 · Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Published
2026-02-11T21:18Z
EPSS history
Timeline
  • 11 FEB 21:18Z
    Prototype pollution in set-in
    cvelistv5