Joomla did bring out a security update for Joomla 2.5 (Joomla 2.5.27)
This release addresses an issue related to the core update component. This release is considered a security release since it includes two resolved security issues associated with 2.5.26.
2.5 End of Life Update
The 2.5 series will reach end of life at the end of 2014, which will mark the end of support for this series. At this time, we project that 2.5.28 will be the last scheduled maintenance release, due in approximately six to eight weeks, the typical timeframe between Joomla! releases.
Please make sure you investigate the possibilities to upgrade your Joomla version to 3.x releases.
Source: Joomla website