# CVE-2019-3887: Denial of service in Kernel

> A guest VM can crash the host kernel via KVM x2APIC MSR access when nested virtualization is enabled, causing denial of service.

- **Severity:** Medium 6.7 (`CVSS:3.0/AV:L/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Apr 2019
- **Updated:** 4 Aug 2024
- **Also known as:** AZL-34854, AZL-6521, DEBIAN-CVE-2019-3887, GHSA-j2cm-6mgm-v7v4, UBUNTU-CVE-2019-3887

## What is CVE-2019-3887?

CVE-2019-3887 is a medium-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 9 Apr 2019. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2019-3887?

It affects 11 products.


Products: Canonical Ubuntu Linux, Fedoraproject Fedora, Linux kernel, Redhat Enterprise Linux, Redhat Enterprise Linux Eus, Redhat Enterprise Linux for Real Time, Redhat Enterprise Linux for Real Time for Nfv, Redhat Enterprise Linux for Real Time for Nfv Tus, Redhat Enterprise Linux for Real Time Tus, Redhat Enterprise Linux Server Aus, Redhat Enterprise Linux Server Tus.

## How do I fix CVE-2019-3887?

Apply the vendor's patch.

## Is CVE-2019-3887 being exploited?

There is no known exploitation of CVE-2019-3887 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-3887 and fix it if it is affected.

What it is: CVE-2019-3887 is a medium-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 9 Apr 2019. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-3887 in the wild and no public exploit code.

Affected product: Canonical Ubuntu Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2019-3887/ (Markdown: https://insights.sbomify.com/CVE-2019-3887/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-3887
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-3887
- OSV: https://osv.dev/vulnerability/CVE-2019-3887

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-3887/
Summaries are generated and may contain mistakes; the official description above is the record.