X.509 Email Address Variable Length Buffer Overflow

Vulnerability Description

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.

References

• https://www.openssl.org/news/secadv/20221101.txt
• https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=c42165b5706e42f67ef8ef4c351a9a4c5d21639a