CVSS Severity (version 2.0):
Impact Subscore: 2.9
Exploitability Subscore: 10.0
CVSS Version 2 Metrics:
Access Vector: Network exploitable
**NOTE: Access Complexity scored Low due to insufficient information
Authentication: Not required to exploit
Impact Type: Allows unauthorized modification
There are four significant mitigating factors.
1) Most enterprise-class certificates, such as VeriSign’s Extended Validation SSL Certificates use the still secure SHA-1 hash function.
2) Certificates already issued with MD5 signatures are not at risk. The exploit only affects new certificate acquisitions.
3) CAs are quickly moving to replace MD5 with SHA-1. For example, VeriSign was planning to phase out MD5 by the end of January 2009. The date was pushed up due to the December proof of concept. On December 31, 2008, RapidSSL certificates shipped with SHA-1 digital signatures.
4)The researchers did not release the under-the-hood specifics of how the exploit was executed.
Source - http://blogs.techrepublic.com.com/security/?p=724&tag=nl.e036