CVE-2026-21710

CVE-2026-21710 vulnerability

CVSS

7.5

EPSS

26.4%

EPSS pct

98th

Exploited

No known

A flaw in Node.js HTTP request handling causes an uncaught `TypeError` when a request is received with a header named `__proto__` and the application accesses `req.headersDistinct`. When this occurs, `dest["__proto__"]` resolves to `Object.prototype` rather than `undefined`, causing `.push()` to be called on a non-array. This exception is thrown synchronously inside a property getter and cannot be intercepted by `error` event listeners, meaning it cannot be handled without wrapping every `req.headersDistinct` access in a `try/catch`. * This vulnerability affects all Node.js HTTP servers on **20.x, 22.x, 24.x, and v25.x**

Affected vendor

See references

Affected product

See references

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness type (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling
CWE-843 — Type Confusion

Published

2026-03-30

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, low attack complexity, requiring no privileges, no user interaction. Successful exploitation leads to high impact to availability.

Its EPSS score of 26.4% reflects a moderate probability of exploitation activity in the wild over the next 30 days, placing it above 98% of all scored CVEs.

Check your external exposure to CVE-2026-21710

Confirm whether the affected software is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2026-21710.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2026-21710

ThreatPort's external attack surface scanner checks your internet-facing assets — agentlessly, from the outside in — for the exposed services and versions that CVE-2026-21710 affects, then prioritises the finding by real risk using CISA KEV and FIRST.org EPSS.

Run a free external exposure scan

Are you exposed to CVE-2026-21710?

Run an instant, non-intrusive external scan to check your attack surface for CVE-2026-21710.

Start free scan

No credit card. Agentless.

Related vulnerabilities

Netweaver Process Integration vulnerability

HIGH

CVE-2019-13481

Dir 818lw Firmware vulnerability