USN-4006-1 fixed a vulnerability in the Linux kernel for Ubuntu 18.10. This update provides the corresponding updates for the Linux Hardware Enablement (HWE) kernel from Ubuntu 18.10 for Ubuntu 18.04 LTS.
Federico Manuel Bento discovered that the Linux kernel did not properly apply Address Space Layout Randomization (ASLR) in some situations for setuid a.out binaries. A local attacker could use this to improve the chances of exploiting an existing vulnerability in a setuid a.out binary.
As a hardening measure, this update disables a.out support.
4.18.0-21.22~18.04.1