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SYNTHESIS OF THE VULNERABILITY

An attacker can ask a trusted certification authority to create an
X.509 v1 certificate, which is accepted by GnuTLS as being a root
certificate.

Impacted products: Unix (platform)

Severity: 1/4

Creation date: 26/02/2014

DESCRIPTION OF THE VULNERABILITY

An X.509 version 1 certificate does not have the basicConstraints
extension. This extension indicates if the certificate if for a
certification authority, and the number of allowed intermediary
certifications authorities. For example:

basicConstraints=critical, CA:TRUE, pathlen:0

However, by default, GnuTLS inferior to 2.7.6 allows v1
certificates.

An attacker can therefore ask a trusted certification authority to
create an X.509 v1 certificate, which is accepted by GnuTLS as
being a root certificate.

ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN

http://vigilance.fr/vulnerability/GnuTLS-accepting-X-509-CA-v1-14311