# CVE-2020-3955: Cross-site scripting in ESXi

> An attacker can execute arbitrary scripts in the ESXi management interface by exploiting improper neutralization of HTML in VM attributes.

- **Severity:** Critical 9.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 29 Apr 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-9g8p-cxgw-6934

## What is CVE-2020-3955?

CVE-2020-3955 is a critical cross-site scripting vulnerability in Vmware Esxi, published on 29 Apr 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

ESXi 6.5 without patch ESXi650-201912104-SG and ESXi 6.7 without patch ESXi670-202004103-SG do not properly neutralize script-related HTML when viewing virtual machines attributes. VMware has evaluated the severity of this issue to be in the Important severity range with a maximum CVSSv3 base score of 8.3.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2020-3955?

It affects 1 product.


Products: Vmware Esxi.

## How do I fix CVE-2020-3955?

No fix has been published for CVE-2020-3955 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-3955 being exploited?

There is no known exploitation of CVE-2020-3955 in the wild and no public exploit code.

## Other vulnerabilities in Vmware Esxi

- [CVE-2026-41709](https://insights.sbomify.com/CVE-2026-41709/): Broadcom VMWare ESX Insufficient Logging (low 2.7, exploited in the wild)
- [CVE-2019-5521](https://insights.sbomify.com/CVE-2019-5521/): Information disclosure in VMware ESXi (critical 9.6)
- [CVE-2024-22252](https://insights.sbomify.com/CVE-2024-22252/): Use-after-free vulnerability (critical 9.3)
- [CVE-2010-4573](https://insights.sbomify.com/CVE-2010-4573/): Auth bypass in n/a (critical 9.3)
- [CVE-2019-5527](https://insights.sbomify.com/CVE-2019-5527/): Use after free in ESXi, Workstation, Fusion, VMRC and Horizon Client (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-3955 and fix it if it is affected.

What it is: CVE-2020-3955 is a critical cross-site scripting vulnerability in Vmware Esxi, published on 29 Apr 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-3955 in the wild and no public exploit code.

Affected product: Vmware Esxi. 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-2020-3955/ (Markdown: https://insights.sbomify.com/CVE-2020-3955/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-3955
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-3955
- OSV: https://osv.dev/vulnerability/CVE-2020-3955

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-3955/
Summaries are generated and may contain mistakes; the official description above is the record.