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CVE-2026-21637

Published: Jan 20, 2026Updated: Jan 30, 2026 Sources: CVE List NVD BDUCWE-400
NVD MITRE
7.5CVSSHIGH
EPSS Score
1.1%
Top 40.0%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

A flaw in Node.js TLS error handling allows remote attackers to crash or exhaust resources of a TLS server when `pskCallback` or `ALPNCallback` are in use. Synchronous exceptions thrown during these callbacks bypass standard TLS error handling paths (tlsClientError and error), causing either immediate process termination or silent file descriptor leaks that eventually lead to denial of service. Because these callbacks process attacker-controlled input during the TLS handshake, a remote client can repeatedly trigger the issue. This vulnerability affects TLS servers using PSK or ALPN callbacks across Node.js versions where these callbacks throw without being safely wrapped.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-400

Affected Products

node.jsnodejsOSS Libraries
nodenodejsOSS Libraries
Node.jsNode.js FoundationOSS Libraries
nodejsoss-projectUSOSS Librariesaka node.js, node
node.js foundationoss-projectUSOSS Librariesaka nodejs foundation, node foundation

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

https://nodejs.org/en/blog/vulnerability/december-2025-security-releases
nodejs.org
https://nodejs.org/en/blog/release/v24.13.0
nodejs.org
https://www.tenable.com/cve/CVE-2026-21637
tenable.com

Timeline

Published
Jan 20, 2026
Last Updated
Jan 30, 2026

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