Expect to see quite a few websites serving error pages today: Nearly 70 percent of websites need to update their core software to fix a pair of vulnerabilities that allow an attacker to seize full control over affected servers. Experts say there are working exploits for the flaws, and that these critical bugs are already being exploited in the wild. Image: Shutterstock.com, Sashkin. The flaws at issue are present in PHP , the programming language that powers sites running on a large number of web publishing systems, including Drupal , Magento , Joomla and WordPress . Earlier today, PHP released an emergency security update to fix two critical bugs that can allow an attacker to execute code of their choosing on a vulnerable server. Reuters reports that government websites in Europe and…