Openswan is a free implementation of Internet Protocol Security (IPsec)and Internet Key Exchange (IKE). IPsec uses strong cryptography to provideboth authentication and encryption services. These services allow you tobuild secure tunnels through untrusted networks.A use-after-free flaw was found in the way Openswan's pluto IKE daemon usedcryptographic helpers. A remote, authenticated attacker could send aspecially-crafted IKE packet that would crash the pluto daemon. This issueonly affected SMP (symmetric multiprocessing) systems that have thecryptographic helpers enabled. The helpers are disabled by default on RedHat Enterprise Linux 5, but enabled by default on Red Hat Enterprise Linux6. (CVE-2011-4073)Red Hat would like to thank the Openswan project for reporting this issue.Upstream acknowledges Petar Tsankov, Mohammad Torabi Dashti and David Basinof the information security group at ETH Zurich as the original reporters.All users of openswan are advised to upgrade to these updated packages,which contain a backported patch to correct this issue. After installingthis update, the ipsec service will be restarted automatically.