Microsoft Security Advisory (2798897) Fraudulent Digital Certificates Could Allow Spoofing

Security Advisory 2798897 released, Certificate Trust List updated - MSRC
New year and new CA compromised - SANS Internet Storm Center
Revoking Trust in Two TurkTrust Certificates - Mozilla Security Blog

For Windows XP and Windows Server 2003 customers, or customers who chose not to install the Certificate Trust List feature, also known as Microsoft Knowledge Base Article 2677070, we recommend that this update be applied immediately using update management software, by checking for updates using the Microsoft Update service, or by downloading and applying the update manually.

Erroneous Certificates - The Opera Rootstore

We will update our rootstore with the new policy, and Opera installations will automatically update during the next week or so. We will additionally blacklist the two sub-CAs, to make any attempted use of them stand out even more for users.

Other rootstores have also responded to this incident: