Description
During certificate verification, OpenSSL (starting from version 1.0.1n and
1.0.2b) will attempt to find an alternative certificate chain if the first
attempt to build such a chain fails. An error in the implementation of
this logic can mean that an attacker could cause certain checks on
untrusted certificates to be bypassed, such as the CA flag, enabling them
to use a valid leaf certificate to act as a CA and "issue" an invalid
certificate (CVE-2015-1793).