USN-3836-1: Linux kernel vulnerabilities

  • USN-3836-1: Linux kernel vulnerabilities

    Ubuntu Security Notices wrote:

    linux, linux-gcp, linux-kvm, linux-raspi2 vulnerabilities

    A security issue affects these releases of Ubuntu and its derivatives:

    • Ubuntu 18.04 LTS


    Several security issues were fixed in the Linux kernel.

    Software Description

    • linux - Linux kernel
    • linux-gcp - Linux kernel for Google Cloud Platform (GCP) systems
    • linux-kvm - Linux kernel for cloud environments
    • linux-raspi2 - Linux kernel for Raspberry Pi 2


    Jann Horn discovered that the Linux kernel mishandles mapping UID or GID ranges inside nested user namespaces in some situations. A local attacker could use this to bypass access controls on resources outside the namespace. (CVE-2018-18955)

    Philipp Wendler discovered that the overlayfs implementation in the Linux kernel did not properly verify the directory contents permissions from within a unprivileged user namespace. A local attacker could use this to expose sensitive information (protected file names). (CVE-2018-6559)

    Update instructions

    The problem can be corrected by updating your system to the following package versions:

    Ubuntu 18.04 LTS
    linux-image-4.15.0-1025-gcp - 4.15.0-1025.26
    linux-image-4.15.0-1027-kvm - 4.15.0-1027.27
    linux-image-4.15.0-1029-raspi2 - 4.15.0-1029.31
    linux-image-4.15.0-42-generic - 4.15.0-42.45
    linux-image-4.15.0-42-generic-lpae - 4.15.0-42.45
    linux-image-4.15.0-42-lowlatency - 4.15.0-42.45
    linux-image-4.15.0-42-snapdragon - 4.15.0-42.45
    linux-image-gcp -
    linux-image-generic -
    linux-image-generic-lpae -
    linux-image-gke -
    linux-image-kvm -
    linux-image-lowlatency -
    linux-image-raspi2 -
    linux-image-snapdragon -

    To update your system, please follow these instructions:

    After a standard system update you need to reboot your computer to make all the necessary changes.

    ATTENTION: Due to an unavoidable ABI change the kernel updates have been given a new version number, which requires you to recompile and reinstall all third party kernel modules you might have installed. Unless you manually uninstalled the standard kernel metapackages (e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual, linux-powerpc), a standard system upgrade will automatically perform this as well.