TLS certificate validation is the process of checking that a server’s certificate is trusted and matches the name a client intended to reach. Clients typically verify the certificate chain against trusted certificate authorities, check validity dates, and confirm the hostname. Encryption alone does not prove who is on the other end; validation helps prevent an attacker from impersonating a server.
In attacks, a compromised or misissued certificate, incorrect hostname checks, or disabled validation can enable man-in-the-middle interception of connections. Defenders should keep trust stores and runtimes updated, preserve certificate and hostname checks, and investigate validation errors rather than bypassing them. In Node.js, flaws in TLS certificate or hostname checking can weaken the trust boundary for outbound connections, so applying fixed runtime releases is important.