Ubuntu Security Notice 2632-1 – Jan Beulich discovered the Xen virtual machine subsystem of the Linux kernel did not properly restrict access to PCI command registers. A local guest user could exploit this flaw to cause a denial of service (host crash). A privilege escalation was discovered in the fork syscall via the int80 entry on 64 bit kernels with 32 bit emulation support. An unprivileged local attacker could exploit this flaw to increase their privileges on the system. Various other issues were also addressed.