CVE-2026-26021
Prototype pollution in npm set-in (<2.0.5) enables Object.prototype pollution via crafted input.
Is CVE-2026-26021 being exploited?
Not confirmed. CVE-2026-26021 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.50% probability of exploitation in the next 30 days.
How severe is CVE-2026-26021?
CVE-2026-26021 is rated Critical with a CVSS score of 9.4. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-26021?
Yes. A fix has been recorded for CVE-2026-26021. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-26021 affect?
CVE-2026-26021 affects Node.js apps using set-in (<2.0.5). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-26021?
Update to 2.0.5+
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Allows pollution of Object.prototype via crafted input, enabling property tampering and potential remote code execution in Node.js apps.
Patch when possible
- affected>= 2.0.1 and < 2.0.5
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.