VulnerabilityAnalyzed

CVE-2026-26021

A prototype pollution vulnerability exists in the the npm package set-in (>=2.0.1, < 2.0.5).

CRITICAL 9.4EPSS 0.50%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.50%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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.

CVSS 4.0: 9.4 CRITICALCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.50% probability · 42th percentile
CISA KEV: Not listed
Weakness: CWE-1321
Affected: set-in project/set-in
Source: security-advisories@github.com

References

https://github.com/ahdinosaur/set-in/commit/b8e1dabfdbd35c8d604b6324e01d03f280256c3dPatch
https://github.com/ahdinosaur/set-in/security/advisories/GHSA-2c4m-g7rx-63q7Exploit, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.