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CVE-2019-11479

Publication date 17 June 2019

Last updated 9 October 2024

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

7.5 · High

Score breakdown

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.

Read the notes from the security team

Mitigation

This can be mitigated by dropping all packets which specify a too small MSS value. For example, to only allow MSS values of greater than 500 bytes, an iptables rule can be specified as: sudo iptables -A INPUT -p tcp -m tcpmss --mss 1:500 -j DROP Note: this will only take effect if the net.ipv4.tcp_mtu_probing sysctl is disabled as well.

Status

Package Ubuntu Release Status
linux 24.04 LTS noble
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
19.10 eoan
Not affected
19.04 disco
Fixed 5.0.0-20.21
18.10 cosmic
Fixed 4.18.0-25.26
18.04 LTS bionic
Fixed 4.15.0-54.58
16.04 LTS xenial
Fixed 4.4.0-154.181
14.04 LTS trusty Ignored ESM criteria, was needed
linux-aws 24.04 LTS noble
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
19.10 eoan
Not affected
19.04 disco
Fixed 5.0.0-1010.11
18.10 cosmic
Fixed 4.18.0-1020.24
18.04 LTS bionic
Fixed 4.15.0-1043.45
16.04 LTS xenial
Fixed 4.4.0-1087.98
14.04 LTS trusty
Not affected
linux-aws-5.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-aws-5.4 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-aws-6.8 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-aws-fips 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Not in release
linux-aws-hwe 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial
Fixed 4.15.0-1043.45~16.04.1
14.04 LTS trusty Not in release
linux-azure 24.04 LTS noble
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
19.10 eoan
Not affected
19.04 disco
Fixed 5.0.0-1010.10
18.10 cosmic
Fixed 4.18.0-1023.24
18.04 LTS bionic
Fixed 4.18.0-1023.24~18.04.1
16.04 LTS xenial
Fixed 4.15.0-1049.54
14.04 LTS trusty
Not affected
linux-azure-4.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-5.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-5.4 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-edge 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.10 cosmic Not in release
18.04 LTS bionic
Fixed 4.18.0-1023.24~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-fde 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal Ignored superseded by linux-azure-fde-5.15
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-fde-5.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-fips 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Not in release
linux-bluefield 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-euclid 19.10 eoan Not in release
19.04 disco Not in release
18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored end of standard support, was needed
14.04 LTS trusty Not in release
linux-fips 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-flo 19.10 eoan Not in release
19.04 disco Not in release
18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Not in release
linux-gcp 24.04 LTS noble
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
19.10 eoan
Not affected
19.04 disco
Fixed 5.0.0-1010.10
18.10 cosmic
Fixed 4.18.0-1015.16
18.04 LTS bionic
Fixed 4.15.0-1036.38
16.04 LTS xenial
Fixed 4.15.0-1036.38~16.04.1
14.04 LTS trusty Not in release
linux-gcp-4.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp-5.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp-5.4 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp-6.8 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp-edge 19.10 eoan Not in release
19.04 disco Not in release
18.10 cosmic Not in release
18.04 LTS bionic
Fixed 4.18.0-1015.16~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp-fips 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Not in release
linux-gke 24.04 LTS noble
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal Ignored end of kernel support
19.10 eoan Not in release
19.04 disco Not in release
18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Not in release
linux-gke-4.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic
Fixed 4.15.0-1036.38
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke-5.0 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gkeop 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gkeop-5.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-goldfish 19.10 eoan Not in release
19.04 disco Not in release
18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Not in release
linux-hwe 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.10 cosmic Not in release
18.04 LTS bionic
Fixed 4.18.0-25.26~18.04.1
16.04 LTS xenial
Fixed 4.15.0-54.58~16.04.1
14.04 LTS trusty Not in release
linux-hwe-5.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-hwe-5.4 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-hwe-6.8 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-hwe-edge 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.10 cosmic Not in release
18.04 LTS bionic
Fixed 5.0.0-20.21~18.04.1
16.04 LTS xenial
Fixed 4.15.0-54.58~16.04.1
14.04 LTS trusty Not in release
linux-ibm 24.04 LTS noble
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-ibm-5.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-ibm-5.4 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-intel 24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-intel-iot-realtime 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-intel-iotg 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-intel-iotg-5.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-iot 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-kvm 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
19.10 eoan
Not affected
19.04 disco
Fixed 5.0.0-1010.11
18.10 cosmic
Fixed 4.18.0-1016.17
18.04 LTS bionic
Fixed 4.15.0-1038.38
16.04 LTS xenial
Fixed 4.4.0-1051.58
14.04 LTS trusty Not in release
linux-lowlatency 24.04 LTS noble
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lowlatency-hwe-5.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lowlatency-hwe-6.8 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-trusty 19.10 eoan Not in release
19.04 disco Not in release
18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-xenial 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty
Not affected
linux-mako 19.10 eoan Not in release
19.04 disco Not in release
18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Not in release
linux-nvidia 24.04 LTS noble
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-nvidia-6.5 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-nvidia-6.8 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-nvidia-lowlatency 24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oem 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
19.10 eoan
Not affected
19.04 disco
Fixed 4.15.0-1045.50
18.10 cosmic Ignored end of life, was pending
18.04 LTS bionic
Fixed 4.15.0-1045.50
16.04 LTS xenial Ignored end of standard support, was needed
14.04 LTS trusty Not in release
linux-oem-6.8 24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oracle 24.04 LTS noble
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
19.10 eoan
Not affected
19.04 disco
Fixed 4.15.0-1017.19
18.10 cosmic Ignored end of life, was pending
18.04 LTS bionic
Fixed 4.15.0-1017.19
16.04 LTS xenial
Fixed 4.15.0-1017.19~16.04.2
14.04 LTS trusty Not in release
linux-oracle-5.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oracle-5.4 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oracle-6.8 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-raspi 24.04 LTS noble
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-raspi-5.4 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-raspi-realtime 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-raspi2 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Ignored replaced by linux-raspi
19.10 eoan
Not affected
19.04 disco
Fixed 5.0.0-1012.12
18.10 cosmic
Fixed 4.18.0-1018.21
18.04 LTS bionic
Fixed 4.15.0-1040.43
16.04 LTS xenial
Fixed 4.4.0-1114.123
14.04 LTS trusty Not in release
linux-realtime 24.04 LTS noble Not in release
22.04 LTS jammy Ignored superseded by Ubuntu Pro ppa version
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-riscv 24.04 LTS noble
Not affected
22.04 LTS jammy Ignored end of kernel support
20.04 LTS focal Ignored superseded by linux-riscv-5.8
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-riscv-5.15 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-riscv-6.8 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-snapdragon 24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
19.10 eoan
Not affected
19.04 disco
Fixed 5.0.0-1016.17
18.10 cosmic Not in release
18.04 LTS bionic
Fixed 4.15.0-1057.62
16.04 LTS xenial
Fixed 4.4.0-1118.124
14.04 LTS trusty Not in release
linux-xilinx-zynqmp 24.04 LTS noble Not in release
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release

Notes

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.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
linux

Severity score breakdown

Parameter Value
Base score 7.5 · High
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact None
Availability impact High
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Related Ubuntu Security Notices (USN)

Other references