CVE-2026-217107.5HighCWE-770

CVE-2026-21710: nodejs vulnerability

nodejs · node

Vendor fix available · Affected: nodejs · Exploitation: likely to be exploited (10% or more)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

25.4%probability of exploitation in the next 30 days

97th percentile

050100

Higher than 97% of scored CVEs

7.5HighCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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 products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

nodejs · nodefrom 20.20.1 up to and including 20.20.1; from 22.22.1 up to and including 22.22.1; from 24.14.0 up to and including 24.14.0; from 25.8.1 up to and including 25.8.1; from 4.0 before 4.*; from 5.0 before 5.* and 14 more

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Likely to be exploited (10% or more). EPSS gives it a 10% or higher chance of exploitation in the next 30 days.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Allocation Without Limits · Denial of Service
Vendor: nodejs
Published: March 2026
Band: Likely to be exploited (10% or more), March 2026
Bounty reports: 1 disclosed on HackerOne

Disclosed bug bounty reports about CVE-2026-21710

The reports on HackerOne that name this CVE, with HackerOne's own outcome. Titles and metadata only.

Denial of Service via `__proto__` header name in `req.headersDistinct` (Uncaught `TypeError` crashes Node.js process)Node.js · 2026 · high severityValid

CoverageNo articles yet

No CyberSIXT article names CVE-2026-21710 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.

References

4 more references are in the CVE record.