Prototype Pollution in Ahdinosaur Set-In
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.
Vulnerability class: Prototype Pollution
EPSS: 0.005 (37.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Ahdinosaur Set-in — versions >= 2.0.1, < 2.0.5
- Set-in_project Set-in
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-26021?
- CVE-2026-26021 is a critical-severity vulnerability in Ahdinosaur Set-In, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 9.8/10. Published 2026-02-11.
- How severe is CVE-2026-26021?
- Critical severity. CVSS v3 base score is 9.8 out of 10.