Updated xen packages that fix one security issue are now available forRed Hat Enterprise Linux 5. The Red Hat Security Response Team has rated this update as having important security impact. A Common Vulnerability Scoring System base score, which gives a detailed severity rating, is available from theCVE link in the References section. The xen packages contain administration tools and the xend service for managing the kernel-xen kernel for virtualization on Red Hat EnterpriseLinux.A flaw was found in the way QEMU emulated the e1000 network interface cardwhen the host was configured to accept jumbo network frames, and a fully-virtualized guest using the e1000 emulated driver was not. A remote attacker could use this flaw to crash the guest or, potentially, execute arbitrary code with root privileges in the guest. All users of xen are advised to upgrade to these updated packages, which correct this issue. After installing the updated packages, all runningfully-virtualized guests must be restarted for this update to take effect.