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Security Advisory

USN-4041-1: Linux kernel update




Canonical Ubuntu

Versions Affected

  • Canonical Ubuntu 16.04


USN-4017-1 fixed vulnerabilities in the Linux kernel for Ubuntu. Unfortunately, the update introduced a regression that interfered with networking applications that setup very low SO_SNDBUF values. This update fixes the problem.

We apologize for the inconvenience.

Jonathan Looney discovered that the Linux kernel could be coerced into segmenting responses into multiple TCP segments. A remote attacker could construct an ongoing sequence of requests to cause a denial of service. 

CVEs contained in this USN include: CVE-2019-11479

Affected Cloud Foundry Products and Versions

Severity is medium unless otherwise noted.

  • Cloud Foundry BOSH xenial-stemcells are vulnerable, including:
    • 315.x versions prior to 315.64
    • 250.x versions prior to 250.79
    • 170.x versions prior to 170.107
    • 97.x versions prior to 97.132
    • All other stemcells not listed.


Users of affected products are strongly encouraged to follow one of the mitigations below:

  • The Cloud Foundry project recommends upgrading the following BOSH xenial-stemcells:
    • Upgrade 315.x versions to 315.64
    • Upgrade 250.x versions to 250.79
    • Upgrade 170.x versions to 170.107
    • Upgrade 97.x versions to 97.132
    • All other stemcells should be upgraded to the latest version available on


Cloud Foundry Foundation Security Team Profile Image

Cloud Foundry Foundation Security Team, AUTHOR