# CVE-2015-2756: Denial of service in n/a

> Local HVM guest users can crash the host by disabling PCI decoding and accessing the device, causing a denial of service.

- **Severity:** Medium 4.9 (`AV:L/AC:L/Au:N/C:N/I:N/A:C`)
- **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:** 1 Apr 2015
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2015-2756, GHSA-vw92-7fxg-964r, UBUNTU-CVE-2015-2756

## What is CVE-2015-2756?

CVE-2015-2756 is a medium-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 1 Apr 2015. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

QEMU, as used in Xen 3.3.x through 4.5.x, does not properly restrict access to PCI command registers, which might allow local HVM guest users to cause a denial of service (non-maskable interrupt and host crash) by disabling the (1) memory or (2) I/O decoding for a PCI Express device and then accessing the device, which triggers an Unsupported Request (UR) response.

Weakness: CWE-264

## Which versions are affected by CVE-2015-2756?

It affects 4 products.


Products: Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Xen Xen.

## How do I fix CVE-2015-2756?

Apply the vendor's patch.

## Is CVE-2015-2756 being exploited?

There is no known exploitation of CVE-2015-2756 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-2015-2756 and fix it if it is affected.

What it is: CVE-2015-2756 is a medium-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 1 Apr 2015. 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-2015-2756 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-2015-2756/ (Markdown: https://insights.sbomify.com/CVE-2015-2756/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2015-2756
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2015-2756
- OSV: https://osv.dev/vulnerability/CVE-2015-2756

---
From sbomify Insights: https://insights.sbomify.com/CVE-2015-2756/
Summaries are generated and may contain mistakes; the official description above is the record.