Severity

High

Vendor

Canonical Ubuntu

Versions Affected

• Canonical Ubuntu 16.04

Description

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.

Mitigation

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 bosh.io.

References

• USN-4017-1
• CVE-2019-11477
• CVE-2019-11478