The MITRE CVE dictionary describes this issue as:
Multiple memory leaks in the OpenSSL extension in PHP before 5.3.6 might allow remote attackers to cause a denial of service (memory consumption) via (1) plaintext data to the openssl_encrypt function or (2) ciphertext data to the openssl_decrypt function.
Find out more about CVE-2011-1468 from the
MITRE CVE dictionary dictionary and
Not vulnerable. This issue did not affect the versions of php as shipped with Red Hat Enterprise Linux 4 and 5. It has been addressed in Red Hat Enterprise Linux 5 (php53) and 6 (php).