CVE-2019-11479

Published: 17 June 2019

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.

From the Ubuntu security team

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.

Priority

Medium

CVSS 3 base score: 7.5

Status

Package Release Status
linux
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.15.0-54.58)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (4.4.0-154.181)
Ubuntu 14.04 ESM (Trusty Tahr) Ignored
(was needed ESM criteria)
Patches:
Introduced by 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Fixed by 5f3e2bf008c2221478101ee72f5cb4654b9fc363
Introduced by 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Fixed by 967c05aee439e6e5d7d805e195b3a20ef5c433d6
linux-aws
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.15.0-1043.45)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (4.4.0-1087.98)
Ubuntu 14.04 ESM (Trusty Tahr)
Released (4.4.0-1048.52)
linux-aws-hwe
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus)
Released (4.15.0-1043.45~16.04.1)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-azure
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.18.0-1023.24~18.04.1)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (4.15.0-1049.54)
Ubuntu 14.04 ESM (Trusty Tahr)
Released (4.15.0-1049.54~14.04.1)
linux-azure-edge
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.18.0-1023.24~18.04.1)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (4.15.0-1049.54)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-euclid
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Ignored
(was needed now end-of-life)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-flo
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Ignored
(abandoned)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-gcp
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.15.0-1036.38)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (4.15.0-1036.38~16.04.1)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-gcp-edge
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.18.0-1015.16~18.04.1)
Ubuntu 16.04 ESM (Xenial Xerus) Does not exist

Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-gke
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Ignored
(end-of-life)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-gke-4.15
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.15.0-1036.38)
Ubuntu 16.04 ESM (Xenial Xerus) Does not exist

Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-gke-5.0
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Not vulnerable
(5.0.0-1011.11~18.04.1)
Ubuntu 16.04 ESM (Xenial Xerus) Does not exist

Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-goldfish
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Ignored
(end-of-life)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-grouper
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Does not exist

Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-hwe
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.18.0-25.26~18.04.1)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (4.15.0-54.58~16.04.1)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-hwe-edge
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (5.0.0-20.21~18.04.1)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (4.15.0-54.58~16.04.1)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-kvm
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.15.0-1038.38)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (4.4.0-1051.58)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-lts-trusty
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Does not exist

Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-lts-utopic
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Does not exist

Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-lts-vivid
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Does not exist

Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-lts-wily
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Does not exist

Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-lts-xenial
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Does not exist

Ubuntu 14.04 ESM (Trusty Tahr)
Released (4.4.0-154.181~14.04.1)
linux-maguro
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Does not exist

Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-mako
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Ignored
(abandoned)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-manta
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver) Does not exist

Ubuntu 16.04 ESM (Xenial Xerus) Does not exist

Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-oem
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.15.0-1045.50)
Ubuntu 16.04 ESM (Xenial Xerus) Ignored
(was needed now end-of-life)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-oracle
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.15.0-1017.19)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (4.15.0-1017.19~16.04.2)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-raspi2
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.15.0-1040.43)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (4.4.0-1114.123)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

linux-snapdragon
Launchpad, Ubuntu, Debian
Upstream
Released (5.2~rc6)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (4.15.0-1057.62)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (4.4.0-1118.124)
Ubuntu 14.04 ESM (Trusty Tahr) Does not exist

Notes

AuthorNote
tyhicks
This issue is primarily due to the TCP spec not defining a minimum
value for the Minimum Segment Size (MSS). The Linux kernel cannot safely put
a restriction on the MSS because it may break valid TCP connections. This
issue will be addressed by allowing a system administrator to raise the
smallest acceptable MSS value but there will be no default mitigation by
default.

References

Bugs