Vulnerability · Published Feb 11, 2026 · Assigned by GitHub_M
CVE-2026-26021Prototype pollution in set-in
Critical 9.4
In plain English
A critical-severity prototype pollution in set-in from ahdinosaur. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | set-in | 2.0.5 | GHSA-2c4m-g7rx-63q7 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| ahdinosaur | set-in | >= 2.0.1, < 2.0.5 |
Weakness: CWE-1321 · 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