--- title: "CVE-2019-19338\n | Ubuntu" description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/CVE-2019-19338?format=md keywords: index, follow --- # CVE-2019-19338 Publication date 13 July 2020 Last updated 4 July 2026 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) ## Cvss 3 Severity Score **5.5 · Medium** [Score breakdown](https://ubuntu.com/security/CVE-2019-19338?format=md#impact-score) Toggle side navigation ## Description 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](https://ubuntu.com/security/CVE-2019-19338?format=md#notes) ## Status Show unmaintained releases | 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 standard support | | 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 standard support | | 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 standard support | | 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 standard support, 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 standard support | | 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 | --- * [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) * [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses) * [Patch details](https://ubuntu.com/security/CVE-2019-19338?format=md#patch-details) ## Notes --- ### [tyhicks](https://launchpad.net/~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?](https://ubuntu.com/security/cves/about#security) | Package | Patch details | | --- | --- | | linux | * Introduced by [1b42f01](https://git.kernel.org/linus/1b42f017415b46c317e71d41c34ec088417a1883), fixed by [e1d38b6](https://git.kernel.org/linus/e1d38b63acd843cfdd4222bf19a26700fd5c699e) | ## Severity score breakdown CVSS version: CVSS v3.0 **Base score** 5.5 · Medium * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Local | | Attack complexity | Low | | Privileges required | Low | | User interaction | None | | Scope | Unchanged | | Confidentiality impact | High | | Integrity impact | None | | Availability impact | None | * Scores | Parameter | Value | | --- | --- | | Base score | 5.5 · Medium | | Exploitability score | - | | Impact score | - | **Vector:** CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-19338) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2019-19338) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2019-19338) * [Debian](https://security-tracker.debian.org/tracker/CVE-2019-19338) ### Other references * *