The MD5 Message-Digest Algorithm is not collision resistant, which makes it easier for context-dependent attackers to conduct spoofing attacks, as demonstrated by attacks on the use of MD5 in the signature algorithm of an X.509 certificate.

References

• http://blog.mozilla.com/security/2008/12/30/md5-weaknesses-could-lead-to-certificate-forgery/
• http://blogs.technet.com/swi/archive/2008/12/30/information-regarding-md5-collisions-problem.aspx
• http://secunia.com/advisories/33826
• http://secunia.com/advisories/34281
• http://secunia.com/advisories/42181
• http://securityreason.com/securityalert/4866
• http://securitytracker.com/id?1024697
• http://www.cisco.com/en/US/products/products_security_response09186a0080a5d24a.html
• http://www.doxpara.com/research/md5/md5_someday.pdf
• http://www.kb.cert.org/vuls/id/836068