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Security Advisory

USN-4363-1: Linux kernel vulnerabilities

USN-4363-1: Linux kernel vulnerabilities




Canonical Ubuntu

Versions Affected

  • Canonical Ubuntu 16.04


It was discovered that the Serial CAN interface driver in the Linux kernel did not properly initialize data. A local attacker could use this to expose sensitive information (kernel memory). (CVE-2020-11494)

It was discovered that the linux kernel did not properly validate certain mount options to the tmpfs virtual memory file system. A local attacker with the ability to specify mount options could use this to cause a denial of service (system crash). (CVE-2020-11565)

David Gibson discovered that the Linux kernel on Power9 CPUs did not properly save and restore Authority Mask registers state in some situations. A local attacker in a guest VM could use this to cause a denial of service (host system crash). (CVE-2020-11669)

It was discovered that the block layer in the Linux kernel contained a race condition leading to a use-after-free vulnerability. A local attacker could possibly use this to cause a denial of service (system crash) or execute arbitrary code. (CVE-2020-12657)

CVEs contained in this USN include: CVE-2020-11494, CVE-2020-11565, CVE-2020-11669, CVE-2020-12657.

Affected Cloud Foundry Products and Versions

Severity is medium unless otherwise noted.

  • Xenial Stemcells
    • 170.x versions prior to 170.220
    • 250.x versions prior to 250.199
    • 315.x versions prior to 315.184
    • 456.x versions prior to 456.113
    • 621.x versions prior to 621.75
    • All other stemcells not listed.


Users of affected products are strongly encouraged to follow the mitigations below. The Cloud Foundry project recommends upgrading the following releases:

  • Xenial Stemcells
    • Upgrade 170.x versions to 170.220 or greater
    • Upgrade 250.x versions to 250.199 or greater
    • Upgrade 315.x versions to 315.184 or greater
    • Upgrade 456.x versions to 456.113 or greater
    • Upgrade 621.x versions to 621.75 or greater
    • All other stemcells should be upgraded to the latest version available on


2020-05-18: Initial vulnerability report published.

Cloud Foundry Foundation Security Team Profile Image

Cloud Foundry Foundation Security Team, AUTHOR