The vio_verify_callback function in viosslfactories.c in MySQL 5.0.x before 5.0.88 and 5.1.x before 5.1.41, when OpenSSL is used, accepts a value of zero for the depth of X.509 certificates, which allows man-in-the-middle attackers to spoof arbitrary SSL-based MySQL servers via a crafted certificate, as demonstrated by a certificate presented by a server linked against the yaSSL library.
bugs.mysql.com/47320
dev.mysql.com/doc/refman/5.0/en/news-5-0-88.html
dev.mysql.com/doc/refman/5.1/en/news-5-1-41.html
lists.mysql.com/commits/87446
lists.opensuse.org/opensuse-security-announce/2010-05/msg00001.html
marc.info/?l=oss-security&m=125881733826437&w=2
www.openwall.com/lists/oss-security/2009/11/19/3
www.openwall.com/lists/oss-security/2009/11/23/16
www.redhat.com/support/errata/RHSA-2010-0109.html
www.vupen.com/english/advisories/2010/1107
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10940
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A8510