CVE-2026-21710
HIGH 7.5EPSS 25.0%
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
- nodejs · node
- CVSS v3.1 CNA
- 7.5 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS v3.0 HACKERONE
- 7.5 HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS
- 25.04% chance of exploitation in the next 30 days, 98th percentile
- Published
- 2026-03-30
- Updated
- 2026-07-15
Proof-of-concept exploits (1)
- open-flaw/CVE-2026-217100★ · 2026-04-01
Security advisories
- https://nodejs.org/en/blog/vulnerability/march-2026-security-releases
- https://access.redhat.com/errata/RHSA-2026:7080
- https://access.redhat.com/errata/RHSA-2026:7123
- https://access.redhat.com/errata/RHSA-2026:7302
- https://access.redhat.com/errata/RHSA-2026:7310
- https://access.redhat.com/errata/RHSA-2026:7350
- https://access.redhat.com/errata/RHSA-2026:7670
- https://access.redhat.com/errata/RHSA-2026:7675
- https://access.redhat.com/errata/RHSA-2026:7896
- https://access.redhat.com/errata/RHSA-2026:7983
- https://access.redhat.com/errata/RHSA-2026:8339
- https://access.redhat.com/errata/RHSA-2026:9711
- https://access.redhat.com/errata/RHSA-2026:9874
- https://access.redhat.com/security/cve/CVE-2026-21710
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-21710.json
- https://bugzilla.redhat.com/show_bug.cgi?id=2453151