Libreswan is an implementation of IPsec & IKE for Linux. IPsec is the Internet Protocol Security and uses strong cryptography to provide both authentication and encryption services. These services allow you to build secure tunnels through untrusted networks such as virtual private network . A flaw was discovered in the way Libreswan"s IKE daemon processed IKE KE payloads. A remote attacker could send specially crafted IKE payload with a KE payload of g^x=0 that, when processed, would lead to a denial of service . This issue was discovered by Paul Wouters of Red Hat. Note: Please note that when upgrading from an earlier version of Libreswan, the existing CA certificates in the /etc/ipsec.d/cacerts/ directory and the existing certificate revocation list files from the /etc/ipsec.d/crls/ directory are automatically imported into the NSS database. Once completed, these directories are no longer used by Libreswan. To install new CA certificates or new CRLS, the certutil and crlutil commands must be used to import these directly into the Network Security Services database. This update also adds the following enhancements: * This update adds support for RFC 7383 IKEv2 Fragmentation, RFC 7619 Auth Null and ID Null, INVALID_KE renegotiation, CRL and OCSP support via NSS, AES_CTR and AES_GCM support for IKEv2, CAVS testing for FIPS compliance. In addition, this update enforces FIPS algorithms restrictions in FIPS mode, and runs Composite Application Validation System testing for FIPS compliance during package build. A new Cryptographic Algorithm Validation Program binary can be used to re-run the CAVS tests at any time. Regardless of FIPS mode, the pluto daemon runs RFC test vectors for various algorithms. Furthermore, compiling on all architectures now enables the "-Werror" GCC option, which enhances the security by making all warnings into errors. * This update also fixes several memory leaks and introduces a sub-second packet retransmit option. * This update improves migration support from Openswan to Libreswan. Specifically, all Openswan options that can take a time value without a suffix are now supported, and several new keywords for use in the /etc/ipsec.conf file have been introduced. See the relevant man pages for details. * With this update, loopback support via the "loopback=" option has been deprecated. All Libreswan users are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add these enhancements.