If you find a security vulnerability in Node.js, please report it to email@example.com. Please withhold public disclosure until after the security team has addressed the vulnerability.
The security team will acknowledge your email within 24 hours. You will receive a more detailed response within 48 hours.
There are no hard and fast rules to determine if a bug is worth reporting as a security issue. Here are some examples of past issues and what the Security Response Team thinks of them. When in doubt, please do send us a report nonetheless.
CVE-2016-7099: Fix invalid wildcard certificate validation check. This was a high-severity defect. It caused Node.js TLS clients to accept invalid wildcard certificates.
#5507: Fix a defect that makes the CacheBleed Attack possible. Many, though not all, OpenSSL vulnerabilities in the TLS/SSL protocols also affect Node.js.
CVE-2016-2216: Fix defects in HTTP header parsing for requests and responses that can allow response splitting. This was a remotely-exploitable defect in the Node.js HTTP implementation.
When in doubt, please do send us a report.