The _json_decode function in plugins/context_reaction_block.inc in the Context module 6.x-2.x before 6.x-3.2 and 7.x-3.x before 7.x-3.0 for Drupal, when using a version of PHP that does not support the json_decode function, allows remote attackers to execute arbitrary PHP code via unspecified vectors related to Ajax operations, possibly involving eval injection.