# CVE-2020-15564: Denial of service in n/a

> A malicious guest administrator can crash the Xen hypervisor on Arm systems by passing a misaligned address to a specific hypercall, causing a denial of service.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:L/AC:L/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:** 7 Jul 2020
- **Updated:** 4 Aug 2024
- **Also known as:** ALPINE-CVE-2020-15564, DEBIAN-CVE-2020-15564, GHSA-m5jw-hjp2-vr52, UBUNTU-CVE-2020-15564

## What is CVE-2020-15564?

CVE-2020-15564 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 7 Jul 2020. 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 4.13.x, allowing Arm guest OS users to cause a hypervisor crash because of a missing alignment check in VCPUOP_register_vcpu_info. The hypercall VCPUOP_register_vcpu_info is used by a guest to register a shared region with the hypervisor. The region will be mapped into Xen address space so it can be directly accessed. On Arm, the region is accessed with instructions that require a specific alignment. Unfortunately, there is no check that the address provided by the guest will be correctly aligned. As a result, a malicious guest could cause a hypervisor crash by passing a misaligned address. A malicious guest administrator may cause a hypervisor crash, resulting in a Denial of Service (DoS). All Xen versions are vulnerable. Only Arm systems are vulnerable. x86 systems are not affected.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2020-15564?

It affects 3 products.


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

## How do I fix CVE-2020-15564?

Apply the vendor's patch.

## Is CVE-2020-15564 being exploited?

There is no known exploitation of CVE-2020-15564 in the wild and no public exploit code.

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- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-15564 and fix it if it is affected.

What it is: CVE-2020-15564 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 7 Jul 2020. 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-2020-15564 in the wild and no public exploit code.

Affected product: Debian Debian 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-2020-15564/ (Markdown: https://insights.sbomify.com/CVE-2020-15564/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-15564
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-15564
- OSV: https://osv.dev/vulnerability/CVE-2020-15564

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-15564/
Summaries are generated and may contain mistakes; the official description above is the record.