classes/GoogleSpell.php in the PHP Spellchecker (aka Google Spellchecker) addon before 2.0.6.1 for TinyMCE, as used in Moodle 2.1.x before 2.1.10, 2.2.x before 2.2.7, 2.3.x before 2.3.4, and 2.4.x before 2.4.1 and other products, does not properly handle control characters, which allows remote attackers to trigger arbitrary outbound HTTP requests via a crafted string.
https://moodle.org/mod/forum/discuss.php?d=220157
https://github.com/tinymce/tinymce_spellchecker_php/commit/22910187bfb9edae90c26e10100d8145b505b974
http://www.tinymce.com/forum/viewtopic.php?id=30036
http://www.tinymce.com/develop/changelog/?type=phpspell
http://openwall.com/lists/oss-security/2013/01/21/1
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-37283