CVE-2026-21637
HIGHCVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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3Description
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.
Analysis
Node.js TLS servers using PSK or ALPN callbacks are vulnerable to denial of service when these callbacks throw unhandled synchronous exceptions during the TLS handshake. Remote attackers can exploit this by sending specially crafted TLS handshake requests to trigger resource exhaustion or process crashes, either through immediate termination or silent file descriptor leaks. …
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Remediation
Within 7 days: Identify all affected systems and apply vendor patches promptly. Monitor vendor channels for patch availability.
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