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CVE-2026-21637
January 20, 2026
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.
Affected Packages
https://github.com/nodejs/node.git (GITHUB):
Affected version(s) >=v22.0.0 <v22.22.0
Fix Suggestion:
Update to version v22.22.0
https://github.com/nodejs/node.git (GITHUB):
Affected version(s) >=v24.0.0 <v24.13.0
Fix Suggestion:
Update to version v24.13.0
https://github.com/nodejs/node.git (GITHUB):
Affected version(s) >=v0.0.1 <v20.20.0
Fix Suggestion:
Update to version v20.20.0
https://github.com/nodejs/node.git (GITHUB):
Affected version(s) >=v25.0.0 <v25.3.0
Fix Suggestion:
Update to version v25.3.0
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CVSS v4
Base Score:
8.2
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.9
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Uncontrolled Resource Consumption
EPSS
Base Score:
0.03