CVE-2019-11479: Canonical Ubuntu Linux

High severity, CVSS 7.5. EPSS: 91.7% chance of exploitation in the next 30 days.

Jonathan Looney discovered that the Linux kernel default MSS is hard-coded to 48 bytes. This allows a remote peer to fragment TCP resend queues significantly more than if a larger MSS were enforced. A remote attacker could use this to cause a denial of service. This has been fixed in stable kernel releases 4.4.182, 4.9.182, 4.14.127, 4.19.52, 5.1.11, and is fixed in commits 967c05aee439e6e5d7d805e195b3a20ef5c433d6 and 5f3e2bf008c2221478101ee72f5cb4654b9fc363.

Affected products

  • Canonical Ubuntu Linux: version 14.04 only; version 16.04 only; version 18.04 only; version 18.10 only; version 19.04 only
  • F5 BIG-IP Access Policy Manager: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IP Advanced Firewall Manager: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IP Analytics: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IP Application Acceleration Manager: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IP Application Security Manager: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IP Domain Name System: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IP Edge Gateway: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IP Fraud Protection Service: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IP Global Traffic Manager: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IP Link Controller: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IP Local Traffic Manager: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IP Policy Enforcement Manager: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IP Webaccelerator: from 11.5.2, before 11.6.5.1 (fixed in 11.6.5.1); from 12.1.0, before 12.1.5.1 (fixed in 12.1.5.1); from 13.1.0, before 13.1.3.2 (fixed in 13.1.3.2); from 14.0.0, before 14.0.1.1 (fixed in 14.0.1.1); from 14.1.2, before 14.1.2.1 (fixed in 14.1.2.1); from 15.0.0, before 15.0.1.1 (fixed in 15.0.1.1)
  • F5 BIG-IQ Centralized Management: from 5.1.0, up to and including 5.4.0; from 6.0.0, up to and including 6.1.0
  • F5 Enterprise Manager: version 3.1.1 only
  • F5 Iworkflow: version 2.3.0 only
  • F5 Traffix Signaling Delivery Controller: from 5.0.0, up to and including 5.1.0
  • Linux Linux Kernel: from 4.4, before 4.4.182 (fixed in 4.4.182); from 4.9, before 4.9.182 (fixed in 4.9.182); from 4.14, before 4.14.127 (fixed in 4.14.127); from 4.19, before 4.19.52 (fixed in 4.19.52); from 5.1, before 5.1.11 (fixed in 5.1.11)
  • Red Hat Enterprise Linux: version 7.0 only
  • Red Hat Virtualization Host: version 4.0 only

Published 2019-06-19. Last modified 2026-06-17.