CVE-2019-19338

Publication date 13 July 2020

Last updated 24 July 2024

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

5.5 · Medium

Score breakdown

A flaw was found in the fix for CVE-2019-11135, in the Linux upstream kernel versions before 5.5 where, the way Intel CPUs handle speculative execution of instructions when a TSX Asynchronous Abort (TAA) error occurs. When a guest is running on a host CPU affected by the TAA flaw (TAA_NO=0), but is not affected by the MDS issue (MDS_NO=1), the guest was to clear the affected buffers by using a VERW instruction mechanism. But when the MDS_NO=1 bit was exported to the guests, the guests did not use the VERW mechanism to clear the affected buffers. This issue affects guests running on Cascade Lake CPUs and requires that host has 'TSX' enabled. Confidentiality of data is the highest threat associated with this vulnerability.

Read the notes from the security team

Status

Package Ubuntu Release Status
linux 19.10 eoan
Not affected
19.04 disco
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Ignored end of ESM support, was ignored [was not-affected (vendor specific) ESM criteria]
linux-aws 19.10 eoan
Not affected
19.04 disco
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Ignored end of ESM support, was ignored [was not-affected (vendor specific) ESM criteria]
linux-aws-5.0 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-aws-hwe 19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-azure 19.10 eoan
Not affected
19.04 disco
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Ignored end of ESM support, was ignored [was not-affected (vendor specific) ESM criteria]
linux-azure-5.3 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-azure-edge 19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Ignored end of standard support, was not-affected
14.04 LTS trusty Not in release
linux-gcp 19.10 eoan
Not affected
19.04 disco
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-gcp-5.3 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-gcp-edge 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-gke-4.15 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-gke-5.0 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-hwe 19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-hwe-edge 19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic Ignored end of life, was not-affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-kvm 19.10 eoan
Not affected
19.04 disco
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-lts-trusty 19.10 eoan Not in release
19.04 disco 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 19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Ignored end of ESM support, was ignored [was not-affected (vendor specific) ESM criteria]
linux-oem 19.10 eoan
Not affected
19.04 disco
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial Ignored end of standard support, was not-affected
14.04 LTS trusty Not in release
linux-oem-osp1 19.10 eoan
Not affected
19.04 disco
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oracle 19.10 eoan
Not affected
19.04 disco
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-oracle-5.0 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-raspi2 19.10 eoan
Not affected
19.04 disco
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-snapdragon 19.10 eoan Not in release
19.04 disco
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release

Notes

tyhicks

This is a vendor specific CVE for kernels that did not include upstream commit e1d38b63acd8 ("kvm/x86: Export MDS_NO=0 to guests when TSX is enabled") and defaulted to leaving TSX enabled. Ubuntu kernels included that commit and disabled TSX where possible as part of the initial TAA mitigations (CVE-2019-11135).

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 5.5 · Medium
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact None
Availability impact None
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N