# CVE-2018-19965: Denial of service in n/a

> A 64-bit PV guest user can crash the host OS by triggering a general protection fault in TLB flushing code due to a flawed Meltdown mitigation.

- **Severity:** Medium 5.6 (`CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Dec 2018
- **Updated:** 5 Aug 2024
- **Also known as:** ALPINE-CVE-2018-19965, DEBIAN-CVE-2018-19965, GHSA-c3g2-qp55-6gjf, UBUNTU-CVE-2018-19965

## What is CVE-2018-19965?

CVE-2018-19965 is a medium-severity denial of service vulnerability in Citrix Xenserver, published on 8 Dec 2018. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An issue was discovered in Xen through 4.11.x allowing 64-bit PV guest OS users to cause a denial of service (host OS crash) because #GP[0] can occur after a non-canonical address is passed to the TLB flushing code. NOTE: this issue exists because of an incorrect CVE-2017-5754 (aka Meltdown) mitigation.

## Which versions are affected by CVE-2018-19965?

It affects 3 products.


Products: Citrix Xenserver, Debian Debian Linux, Xen Xen.

## How do I fix CVE-2018-19965?

Apply the vendor's patch.

## Is CVE-2018-19965 being exploited?

There is no known exploitation of CVE-2018-19965 in the wild and no public exploit code.

## Other vulnerabilities in Citrix Xenserver

- [CVE-2014-4947](https://insights.sbomify.com/CVE-2014-4947/): Memory corruption in n/a (critical 10.0)
- [CVE-2018-14007](https://insights.sbomify.com/CVE-2018-14007/): Path traversal in n/a (critical 9.8)
- [CVE-2015-7705](https://insights.sbomify.com/CVE-2015-7705/): Denial of service in n/a (critical 9.8)
- [CVE-2016-5302](https://insights.sbomify.com/CVE-2016-5302/): Auth bypass in n/a (critical 9.8)
- [CVE-2017-12134](https://insights.sbomify.com/CVE-2017-12134/): Memory corruption in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-19965 and fix it if it is affected.

What it is: CVE-2018-19965 is a medium-severity denial of service vulnerability in Citrix Xenserver, published on 8 Dec 2018. 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-2018-19965 in the wild and no public exploit code.

Affected product: Citrix Xenserver. 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-2018-19965/ (Markdown: https://insights.sbomify.com/CVE-2018-19965/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-19965
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-19965
- OSV: https://osv.dev/vulnerability/CVE-2018-19965

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-19965/
Summaries are generated and may contain mistakes; the official description above is the record.