OpenSSL is a toolkit that implements the Secure Sockets Layer and Transport Layer Security protocols, as well as a full-strength, general purpose cryptography library. It was discovered that OpenSSL leaked timing information when decrypting TLS/SSL and DTLS protocol encrypted records when CBC-mode cipher suites were used. A remote attacker could possibly use this flaw to retrieve plain text from the encrypted packets by using a TLS/SSL or DTLS server as a padding oracle. A NULL pointer dereference flaw was found in the OCSP response verification in OpenSSL. A malicious OCSP server could use this flaw to crash applications performing OCSP verification by sending a specially-crafted response. It was discovered that the TLS/SSL protocol could leak information about plain text when optional compression was used. An attacker able to control part of the plain text sent over an encrypted TLS/SSL connection could possibly use this flaw to recover other portions of the plain text. Note: This update disables zlib compression, which was previously enabled in OpenSSL by default. Applications using OpenSSL now need to explicitly enable zlib compression to use it. It was found that OpenSSL read certain environment variables even when used by a privileged application. A local attacker could use this flaw to escalate their privileges. No application shipped with Red Hat Enterprise Linux 5 and 6 was affected by this problem. All OpenSSL users should upgrade to these updated packages, which contain backported patches to resolve these issues. For the update to take effect, all services linked to the OpenSSL library must be restarted, or the system rebooted.