[RUSTSEC-2022-0065] X.509 Email Address Variable Length Buffer Overflow

A buffer overrun can be triggered in X.509 certificate verification,
specifically in name constraint checking. Note that this occurs after
certificate chain signature verification and requires either a CA to
have signed a malicious certificate or for an application to continue
certificate verification despite failure to construct a path to a trusted
issuer. An attacker can craft a malicious email address in a certificate
to overflow an arbitrary number of bytes containing the . character
(decimal 46) on the stack. This buffer overflow could result in a crash
(causing a denial of service).

In a TLS client, this can be triggered by connecting to a malicious
server. In a TLS server, this can be triggered if the server requests
client authentication and a malicious client connects.