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CVE-2026-21710
ANC
HighConfirmedExploit available

A flaw in Node.js HTTP request handling causes an uncaught `TypeError` when a request is received with a header named `__proto__` and the a…

CVSS
7.5
High
EPSS
0.13
p95
Published
2026-01-01
Updated
2026-01-01
Description

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**

Tags · CWE
Pre-auth
CWE-770
CAPEC-125
CAPEC-130
CAPEC-147
CAPEC-197
CAPEC-229
CAPEC-230
CAPEC-231
CAPEC-469
CAPEC-482
CAPEC-486
CAPEC-487
CAPEC-488
CAPEC-489
CAPEC-490
CAPEC-491
CAPEC-493
CAPEC-494
CAPEC-495
CAPEC-496
CAPEC-528
Affected products
NodejsNodejs
CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Timeline
2026-01-01
Published
2026-01-01
Updated
CVSS 3.1 breakdown
Attack Vector
AV: N
Network (N)
Attack Complexity
AC: L
Low (L)
Privileges Required
PR: N
None (N)
User Interaction
UI: N
None (N)
Scope
S: U
Unchanged (U)
Confidentiality Impact
C: N
None (N)
Integrity Impact
I: N
None (N)
Availability Impact
A: H
High (H)
Exploit indicators
EPSS
0.131 · p95
Known exploited (KEV)
No
MITRE ATT&CK
Inferred via CAPEC
└ via CAPEC-125 · CWE-770
└ via CAPEC-490 · CWE-770
└ via CAPEC-125 · CWE-770
└ via CAPEC-482 · CWE-770
└ via CAPEC-469 · CWE-770
└ via CAPEC-130 · CWE-770
Known exploits — Сканер-ВС
CVE-2026-21710
github-poc · https://github.com/dajneem23/CVE-2026-21710
Enterprise
Affected products
ProductVendorStatus
Tracked
nodejsTracked
nodejsTracked
Source databases
ANC
DEB
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