# CVE-2023-4155: Sev-es / sev-snp vmgexit double fetch vulnerability

> A double fetch race condition in KVM SEV allows guest attackers to cause stack overflow, leading to denial of service or potential host escape.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Sep 2023
- **Updated:** 27 Feb 2025
- **Also known as:** AZL-29700, DEBIAN-CVE-2023-4155, GHSA-7f5q-x8vx-pfrp, UBUNTU-CVE-2023-4155

## What is CVE-2023-4155?

CVE-2023-4155 is a medium-severity vulnerability in Fedoraproject Fedora, published on 13 Sep 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A flaw was found in KVM AMD Secure Encrypted Virtualization (SEV) in the Linux kernel. A KVM guest using SEV-ES or SEV-SNP with multiple vCPUs can trigger a double fetch race condition vulnerability and invoke the `VMGEXIT` handler recursively. If an attacker manages to call the handler multiple times, they can trigger a stack overflow and cause a denial of service or potentially guest-to-host escape in kernel configurations without stack guard pages (`CONFIG_VMAP_STACK`).

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2023-4155?

It affects 3 products.


Products: Fedoraproject Fedora, Linux kernel, Redhat Enterprise Linux.

## How do I fix CVE-2023-4155?

Apply the vendor's patch.

## Is CVE-2023-4155 being exploited?

There is no known exploitation of CVE-2023-4155 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-4155 and fix it if it is affected.

What it is: CVE-2023-4155 is a medium-severity vulnerability in Fedoraproject Fedora, published on 13 Sep 2023. 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-2023-4155 in the wild and no public exploit code.

Affected product: Fedoraproject Fedora. 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-2023-4155/ (Markdown: https://insights.sbomify.com/CVE-2023-4155/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-4155
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-4155
- OSV: https://osv.dev/vulnerability/CVE-2023-4155

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-4155/
Summaries are generated and may contain mistakes; the official description above is the record.