# CVE-2021-21974: Memory corruption in VMware Cloud Foundation

> A heap-overflow in OpenSLP allows remote code execution on ESXi hosts by attackers on the same network segment.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Feb 2021
- **Updated:** 2 Jun 2026
- **Also known as:** GHSA-4mwc-fv8c-wp9f

## What is CVE-2021-21974?

CVE-2021-21974 is a high-severity memory corruption vulnerability in Vmware Cloud Foundation, published on 24 Feb 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

OpenSLP as used in ESXi (7.0 before ESXi70U1c-17325551, 6.7 before ESXi670-202102401-SG, 6.5 before ESXi650-202102101-SG) has a heap-overflow vulnerability. A malicious actor residing within the same network segment as ESXi who has access to port 427 may be able to trigger the heap-overflow issue in OpenSLP service resulting in remote code execution.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-21974?

It affects 2 products.


Products: Vmware Cloud Foundation, Vmware Esxi.

## How do I fix CVE-2021-21974?

No fix has been published for CVE-2021-21974 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-21974 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-21974 exists.

Public exploit code:

- POC for CVE-2021-21974 VMWare ESXi RCE Exploit (github_poc): https://github.com/Shadow0ps/CVE-2021-21974
- 自研针对ESXI 堆栈溢出的CVE-2021-21974 POC，只支持项目给出的的目标和环境，用于学习和研究 (github_poc): https://github.com/Aiyakami/CVE-2021-21974
- Analysis of the ransom demands from Shodan results (github_poc): https://github.com/n2x4/Feb2023-CVE-2021-21974-OSINT
- ESXi EZ - A custom scanner that takes list of IPs either in JSON, CSV or individually  and checks for infection CVE-2021-21974 (github_poc): https://github.com/CYBERTHREATANALYSIS/ESXi-Ransomware-Scanner-mi
- Nmap NSE script for cve-2021-21974 (github_poc): https://github.com/hateme021202/cve-2021-21974
- https://github.com/mercylessghost/CVE-2021-21974 (github_poc): https://github.com/mercylessghost/CVE-2021-21974

## Other vulnerabilities in Vmware Cloud Foundation

- [CVE-2024-38812](https://insights.sbomify.com/CVE-2024-38812/): VMware vCenter Server Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-37079](https://insights.sbomify.com/CVE-2024-37079/): Broadcom VMware vCenter Server Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2022-22954](https://insights.sbomify.com/CVE-2022-22954/): VMware Workspace ONE Access and Identity Manager Server-Side Template Injection (critical 9.8, exploited in the wild)
- [CVE-2021-22005](https://insights.sbomify.com/CVE-2021-22005/): VMware vCenter Server File Upload (critical 9.8, exploited in the wild)
- [CVE-2021-21985](https://insights.sbomify.com/CVE-2021-21985/): VMware vCenter Server Improper Input Validation (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-21974 and fix it if it is affected.

What it is: CVE-2021-21974 is a high-severity memory corruption vulnerability in Vmware Cloud Foundation, published on 24 Feb 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-21974 exists.

Affected product: Vmware Cloud Foundation. 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-2021-21974/ (Markdown: https://insights.sbomify.com/CVE-2021-21974/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21974
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21974
- OSV: https://osv.dev/vulnerability/CVE-2021-21974

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-21974/
Summaries are generated and may contain mistakes; the official description above is the record.