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Security Advisory

USN-4017-1: Linux kernel vulnerabilities


USN-4017-1: Linux kernel vulnerabilities




Canonical Ubuntu

Versions Affected

  • Canonical Ubuntu 16.04


Jonathan Looney discovered that the TCP retransmission queue implementation in the Linux kernel could be fragmented when handling certain TCP Selective Acknowledgment (SACK) sequences. A remote attacker could use this to cause a denial of service. (CVE-2019-11478)

Jonathan Looney discovered that an integer overflow existed in the Linux kernel when handling TCP Selective Acknowledgments (SACKs). A remote attacker could use this to cause a denial of service (system crash). (CVE-2019-11477)

CVEs contained in this USN include: CVE-2019-11477, CVE-2019-11478

Affected Cloud Foundry Products and Versions

Severity is high unless otherwise noted.

  • Cloud Foundry BOSH xenial-stemcells are vulnerable, including:
    • 315.x versions prior to 315.41
    • 250.x versions prior to 250.63
    • 170.x versions prior to 170.93
    • 97.x versions prior to 97.113
    • 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 315.41
    • Upgrade 250.x versions to 250.63
    • Upgrade 170.x versions to 170.93
    • Upgrade 97.x versions to 97.113
    • 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