CVE-2007-1521

CVE-2007-1521 is a double free vulnerability affecting PHP versions before 4.4.7 and 5.x before 5.2.2. This flaw allows attackers to execute arbitrary code by interrupting the session_regenerate_id function, for instance, by triggering a memory limit violation or calling a userspace error handler. With a CVSS score of 6.8, it is a medium-severity vulnerability that can be exploited remotely with medium attack complexity, potentially leading to partial compromise of confidentiality, integrity, and availability. While not listed on the KEV catalog or Hot List, an exploit for PHP 5.2.1 has been published on ExploitDB, though there is no evidence of active exploitation, Metasploit modules, or significant community discussion or media coverage.