A PHP object injection vulnerability exists in SugarCRM versions prior to 6.5.24, 6.7.13, 7.5.2.5, 7.6.2.2, and 7.7.1.0 due to improper validation of PHP serialized input in the SugarRestSerialize.php script. The vulnerable code fails to sanitize the rest_data parameter before passing it to the unserialize() function. This allows an unauthenticated attacker to submit crafted serialized data containing malicious object declarations, resulting in arbitrary code execution within the application context. Although SugarCRM released a prior fix in advisory sugarcrm-sa-2016-001, the patch was incomplete and failed to address some vectors.