# CVE-2026-27211: Cloud Hypervisor: Host File Exfiltration via QCOW Backing File Abuse

> A malicious guest can exfiltrate arbitrary host files by abusing QCOW2 backing file detection in Cloud Hypervisor when using writable or untrusted disk images.

- **Severity:** Critical 9.1 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Feb 2026
- **Updated:** 25 Feb 2026
- **Also known as:** AZL-78282, GHSA-jmr4-g2hv-mjj6

## What is CVE-2026-27211?

CVE-2026-27211 is a critical path traversal vulnerability in cloud-hypervisor, published on 21 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Cloud Hypervisor is a Virtual Machine Monitor for Cloud workloads. Versions 34.0 through 50.0 arevulnerable to arbitrary host file exfiltration (constrained by process privileges) when using virtio-block devices backed by raw images. A malicious guest can overwrite its disk header with a crafted QCOW2 structure pointing to a sensitive host path. Upon the next VM boot or disk scan, the image format auto-detection parses this header and serves the host file's contents to the guest. Guest-initiated VM reboots are sufficient to trigger a disk scan and do not cause the Cloud Hypervisor process to exit. Therefore, a single VM can perform this attack without needing interaction from the management stack. Successful exploitation requires the backing image to be either writable by the guest or sourced from an untrusted origin. Deployments utilizing only trusted, read-only images are not affected. This issue has been fixed in version 50.1. To workaround, enable land lock sandboxing and restrict process privileges and access.

Weakness: CWE-73 (External Control of File Name or Path)

## Which versions are affected by CVE-2026-27211?

It affects 1 product.


Products: Cloudhypervisor Cloud Hypervisor.

## How do I fix CVE-2026-27211?

Upgrade to a fixed version.

## Is CVE-2026-27211 being exploited?

There is no known exploitation of CVE-2026-27211 in the wild and no public exploit code.

## Other vulnerabilities in cloud-hypervisor

- [CVE-2023-30612](https://insights.sbomify.com/CVE-2023-30612/): Malicious HTTP requests could close arbitrary opening file descriptors in cloud-hypervisor (medium 4.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-27211 and fix it if it is affected.

What it is: CVE-2026-27211 is a critical path traversal vulnerability in cloud-hypervisor, published on 21 Feb 2026. 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-2026-27211 in the wild and no public exploit code.

Affected product: cloud-hypervisor. 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-2026-27211/ (Markdown: https://insights.sbomify.com/CVE-2026-27211/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-27211
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27211
- OSV: https://osv.dev/vulnerability/CVE-2026-27211

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-27211/
Summaries are generated and may contain mistakes; the official description above is the record.