Use-after-free vulnerability in the process_nested_data function in ext/standard/var_unserializer.re in PHP before 5.4.36, 5.5.x before 5.5.20, and 5.6.x before 5.6.4 allows remote attackers to execute arbitrary code via a crafted unserialize call that leverages improper handling of duplicate keys within the serialized properties of an object, a different vulnerability than CVE-2004-1019.

The deserialization code in PHP before 4.3.10 and PHP 5.x up to 5.0.2 allows remote attackers to cause a denial of service and execute arbitrary code via untrusted data to the unserialize function that may trigger "information disclosure, double-free and negative reference index array underflow" results.