# CVE-2015-8555: Information disclosure in n/a

> Local guest domains can read sensitive information from other domains due to uninitialized FPU and XMM registers in Xen hypervisor.

- **Severity:** High 8.6 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Apr 2016
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2015-8555, GHSA-ffhp-28g8-p5m9, UBUNTU-CVE-2015-8555

## What is CVE-2015-8555?

CVE-2015-8555 is a high-severity vulnerability in Citrix Xenserver, published on 13 Apr 2016. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Xen 4.6.x, 4.5.x, 4.4.x, 4.3.x, and earlier do not initialize x86 FPU stack and XMM registers when XSAVE/XRSTOR are not used to manage guest extended register state, which allows local guest domains to obtain sensitive information from other domains via unspecified vectors.

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2015-8555?

It affects 2 products.


Products: Citrix Xenserver, Xen Xen.

## How do I fix CVE-2015-8555?

Apply the vendor's patch.

## Is CVE-2015-8555 being exploited?

There is no known exploitation of CVE-2015-8555 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-2015-8555 and fix it if it is affected.

What it is: CVE-2015-8555 is a high-severity vulnerability in Citrix Xenserver, published on 13 Apr 2016. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2015-8555 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-2015-8555/ (Markdown: https://insights.sbomify.com/CVE-2015-8555/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2015-8555
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2015-8555
- OSV: https://osv.dev/vulnerability/CVE-2015-8555

---
From sbomify Insights: https://insights.sbomify.com/CVE-2015-8555/
Summaries are generated and may contain mistakes; the official description above is the record.