--- title: "CVE-2019-3887\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-2019-3887?format=md keywords: index, follow --- # CVE-2019-3887 Publication date 9 April 2019 Last updated 4 July 2026 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) ## Cvss 3 Severity Score **5.6 · Medium** [Score breakdown](https://ubuntu.com/security/CVE-2019-3887?format=md#impact-score) Toggle side navigation ## Description A flaw was found in the way KVM hypervisor handled x2APIC Machine Specific Rregister (MSR) access with nested(=1) virtualization enabled. In that, L1 guest could access L0's APIC register values via L2 guest, when 'virtualize x2APIC mode' is enabled. A guest could use this flaw to potentially crash the host kernel resulting in DoS issue. Kernel versions from 4.16 and newer are vulnerable to this issue. ### From the Ubuntu Security Team Marc Orr discovered that the KVM hypervisor implementation in the Linux kernel did not properly restrict APIC MSR register values when nested virtualization is used. An attacker in a guest vm could use this to cause a denial of service (host OS crash). [Read the notes from the security team](https://ubuntu.com/security/CVE-2019-3887?format=md#notes) ## Mitigation If qemu is installed, to prevent nested virtualization from being enabled, set "options kvm\_intel nested=0" in /etc/modprobe.d/qemu-system-x86.conf ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | linux | 19.04 disco | Fixed 5.0.0-15.16 | | 18.10 cosmic | Fixed 4.18.0-20.21 | | 18.04 LTS bionic | Not affected | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Not affected | | linux-aws | 19.04 disco | Fixed 5.0.0-1006.6 | | 18.10 cosmic | Fixed 4.18.0-1016.18 | | 18.04 LTS bionic | Not affected | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Not affected | | linux-aws-hwe | 19.04 disco | Not in release | | 18.10 cosmic | 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 | 19.04 disco | Fixed 5.0.0-1006.6 | | 18.10 cosmic | Fixed 4.18.0-1018.18 | | 18.04 LTS bionic | Fixed 4.18.0-1018.18~18.04.1 | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Not affected | | linux-azure-edge | 19.04 disco | Not in release | | 18.10 cosmic | Not in release | | 18.04 LTS bionic | Fixed 4.18.0-1018.18~18.04.1 | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Not in release | | linux-euclid | 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-flo | 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-gcp | 19.04 disco | Fixed 5.0.0-1006.6 | | 18.10 cosmic | Fixed 4.18.0-1011.12 | | 18.04 LTS bionic | Not affected | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Not in release | | linux-gcp-edge | 19.04 disco | Not in release | | 18.10 cosmic | Not in release | | 18.04 LTS bionic | Fixed 4.18.0-1011.12~18.04.1 | | 16.04 LTS xenial | Not in release | | 14.04 LTS trusty | Not in release | | linux-gke | 19.04 disco | Not in release | | 18.10 cosmic | Not in release | | 18.04 LTS bionic | Not affected | | 16.04 LTS xenial | Ignored end of standard support | | 14.04 LTS trusty | Not in release | | linux-goldfish | 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-grouper | 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-hwe | 19.04 disco | Not in release | | 18.10 cosmic | Not in release | | 18.04 LTS bionic | Fixed 4.18.0-20.21~18.04.1 | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Not in release | | linux-hwe-edge | 19.04 disco | Not in release | | 18.10 cosmic | Not in release | | 18.04 LTS bionic | Not affected | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Not in release | | linux-kvm | 19.04 disco | Fixed 5.0.0-1006.6 | | 18.10 cosmic | Fixed 4.18.0-1012.12 | | 18.04 LTS bionic | Not affected | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Not in release | | linux-lts-trusty | 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-utopic | 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-vivid | 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-wily | 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 | 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-maguro | 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-mako | 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-manta | 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-oem | 19.04 disco | Not affected | | 18.10 cosmic | Not affected | | 18.04 LTS bionic | Not affected | | 16.04 LTS xenial | Ignored end of standard support, was needs-triage | | 14.04 LTS trusty | Not in release | | linux-oracle | 19.04 disco | Not affected | | 18.10 cosmic | Not affected | | 18.04 LTS bionic | Not affected | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Not in release | | linux-raspi2 | 19.04 disco | Fixed 5.0.0-1008.8 | | 18.10 cosmic | Fixed 4.18.0-1014.16 | | 18.04 LTS bionic | Not affected | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Not in release | | linux-snapdragon | 19.04 disco | Fixed 5.0.0-1012.12 | | 18.10 cosmic | Not in release | | 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-2019-3887?format=md#patch-details) ## Notes --- ### [tyhicks](https://launchpad.net/~tyhicks) Ubuntu kernels do not enable nested KVM virtualization by default and are unaffected by this flaw in the default configuration. However, installing QEMU results in nested KVM support to be enabled via the /etc/modprobe.d/qemu-system-x86.conf file. To ensure that nested virtualization is not enabled, verify that the /sys/module/kvm\_intel/parameters/nested file contains "N". ### 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 [15303ba](https://git.kernel.org/linus/15303ba5d1cd9b28d03a980456c0978c0ea3b208), fixed by [acff784](https://git.kernel.org/linus/acff78477b9b4f26ecdf65733a4ed77fe837e9dc) * Introduced by [c992384](https://git.kernel.org/linus/c992384bde84fb2f0318bdb4f6c710605dd7a217), fixed by [c73f4c9](https://git.kernel.org/linus/c73f4c998e1fd4249b9edfa39e23f4fda2b9b041) | ## Severity score breakdown CVSS version: CVSS v3.0 **Base score** 5.6 · Medium * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Local | | Attack complexity | High | | Privileges required | Low | | User interaction | None | | Scope | Changed | | Confidentiality impact | None | | Integrity impact | None | | Availability impact | High | * Scores | Parameter | Value | | --- | --- | | Base score | 5.6 · Medium | | Exploitability score | - | | Impact score | - | **Vector:** CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-3887) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2019-3887) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2019-3887) * [Debian](https://security-tracker.debian.org/tracker/CVE-2019-3887) ### Related Ubuntu Security Notices (USN) + [USN-3980-1](https://usn.ubuntu.com/USN-3980-1) + Linux kernel vulnerabilities + 14 May 2019 + [USN-3980-2](https://usn.ubuntu.com/USN-3980-2) + Linux kernel (HWE) vulnerabilities + 14 May 2019 + [USN-3979-1](https://usn.ubuntu.com/USN-3979-1) + Linux kernel vulnerabilities + 14 May 2019 ### Other references * *