# CVE-2016-4963: Denial of service in n/a

> Local guest users can cause denial of service in Xen management tools by manipulating xenstore backend directories.

- **Severity:** Medium 4.7 (`CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/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:** 7 Jun 2016
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2016-4963, GHSA-4wh7-gxf5-7gc2, UBUNTU-CVE-2016-4963

## What is CVE-2016-4963?

CVE-2016-4963 is a medium-severity denial of service vulnerability in Xen Xen, published on 7 Jun 2016. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The libxl device-handling in Xen through 4.6.x allows local guest OS users with access to the driver domain to cause a denial of service (management tool confusion) by manipulating information in the backend directories in xenstore.

Weakness: CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2016-4963?

It affects 1 product.


Products: Xen Xen.

## How do I fix CVE-2016-4963?

Apply the vendor's patch.

## Is CVE-2016-4963 being exploited?

There is no known exploitation of CVE-2016-4963 in the wild and no public exploit code.

## Other vulnerabilities in Xen Xen

- [CVE-2017-10912](https://insights.sbomify.com/CVE-2017-10912/): Privilege escalation in n/a (critical 10.0)
- [CVE-2017-10918](https://insights.sbomify.com/CVE-2017-10918/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-10920](https://insights.sbomify.com/CVE-2017-10920/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-10921](https://insights.sbomify.com/CVE-2017-10921/): Memory corruption in n/a (critical 10.0)
- [CVE-2025-27466](https://insights.sbomify.com/CVE-2025-27466/): Mutiple vulnerabilities in the Viridian interface (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-4963 and fix it if it is affected.

What it is: CVE-2016-4963 is a medium-severity denial of service vulnerability in Xen Xen, published on 7 Jun 2016. 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-2016-4963 in the wild and no public exploit code.

Affected product: Xen Xen. 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-2016-4963/ (Markdown: https://insights.sbomify.com/CVE-2016-4963/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-4963
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-4963
- OSV: https://osv.dev/vulnerability/CVE-2016-4963

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-4963/
Summaries are generated and may contain mistakes; the official description above is the record.