The session extension in PHP 4 before 4.4.5, and PHP 5 before 5.2.1, calculates the reference count for the session variables without considering the internal pointer from the session globals, which allows context-dependent attackers to execute arbitrary code via a crafted string in the session_register after unsetting HTTP_SESSION_VARS and _SESSION, which destroys the session data Hashtable.
Severity
High 7.5
Published
27 Mar 2007
Last changed
16 Jun 2026
Added to UpHeron
14 Oct 2026
Exploit chance
9.1% in the next 30 daysHigher than 95% of CVEs. EPSS by FIRST, 12 Nov 2026