Detections
Analytics
CVE-2026-21637
high
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. Impact: Thank you, to 0xmaxhax for reporting this vulnerability and thank you mcollina for fixing it.
References
https://nodejs.org/en/blog/vulnerability/december-2025-security-releases