Moodle 2.5.9 release notes
From MoodleDocs
This version of Moodle is no longer supported. You are encouraged to upgrade to a supported version of Moodle.
Releases > Moodle 2.5.9 release notes
Release date: 10 November, 2014
Here is the full list of fixed issues in 2.5.9.
Security issues
A number of security related issues were resolved. Details of these issues will be released after a period of approximately one week to allow system administrators to safely update to the latest version.