Today, we are releasing XenForo 1.2.6 to address a potential security vulnerability that has been identified. We recommend that all customers running XenForo 1.2 or earlier upgrade to 1.2.6 as soon as possible. This fix changes a large number of files so a full upgrade is required.
Please note that in order to resolve this security issue, XenForo's PHP requirements needed to increase slightly. This release now requires PHP 5.2.11 or higher.
The security issue relates to XML processing. A specially crafted XML file can be used to enact a denial of service attack or potentially read files from the the file system. This type of vulnerability has been identified in many other applications. In XenForo, the risk is mitigated as only...