OpenSSL: Alternate chains certificate forgery

Background

OpenSSL is an Open Source toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) as well as a general purpose cryptography library.

Description

During certificate verification, OpenSSL attempts to find an alternative certificate chain if the first attempt to build such a chain fails.

Impact

A remote 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.

Workaround

There is no known workaround at this time.

Resolution

All OpenSSL users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=dev-libs/openssl-1.0.1p"