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.
git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-37283
openwall.com/lists/oss-security/2013/01/21/1
www.tinymce.com/develop/changelog/?type=phpspell
www.tinymce.com/forum/viewtopic.php?id=30036
github.com/tinymce/tinymce_spellchecker_php/commit/22910187bfb9edae90c26e10100d8145b505b974
moodle.org/mod/forum/discuss.php?d=220157