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CVE-2026-26021

Set-in vulnerability

9.8 CRITICALPublic exploitEPSS 0.56%
  1. Published11 Feb 2026

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 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Set-in≥ 2.0.1 < 2.0.5

Remediation

Fixed in
Set-in≥ 2.0.5

References

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Frequently asked

Is CVE-2026-26021 being actively exploited?

CVE-2026-26021 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.56%.

How severe is CVE-2026-26021?

CVE-2026-26021 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.56% probability of exploitation.

Which products are affected by CVE-2026-26021?

Affected products include Set-in.

How do I fix CVE-2026-26021?

Upgrade affected software to a fixed version, for example Set-in 2.0.5 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.