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CVE-2026-21637

CVE-2026-21637 HackerOne: CVE-2026-21637 TLS PSK/ALPN Callback Exceptions Bypass Error Handlers

[CVE-2026-21637](https://www.cve.org/CVERecord?id=CVE-2026-21637) is regarding a vulnerability 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 call

Tuesday, April 14, 2026Vulnios Threat Intelligence
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Executive Summary

CVE-2026-21637 is regarding a vulnerability 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 call

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