# CVE-2021-36833: WordPress MC4WP plugin <= 4.8.6 - Authenticated Stored Cross-Site Scripting (XSS) vulnerability

> Authenticated administrators can inject malicious scripts into the MC4WP WordPress plugin, potentially compromising user sessions or site integrity.

- **Severity:** Medium 4.8 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 20 May 2022
- **Updated:** 28 Apr 2026
- **Also known as:** GHSA-xhfm-f7f9-cpx6

## What is CVE-2021-36833?

CVE-2021-36833 is a medium-severity cross-site scripting vulnerability in ibericode MC4WP: Mailchimp for WordPress, published on 20 May 2022. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

Authenticated (admin or higher user role) Stored Cross-Site Scripting (XSS) vulnerability in ibericode's MC4WP plugin <= 4.8.6 at WordPress.

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

## Which versions are affected by CVE-2021-36833?

It affects 1 product.


Products: Ibericode Mailchimp for Wordpress.

## How do I fix CVE-2021-36833?

No fix has been published for CVE-2021-36833 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-36833 being exploited?

There is no known exploitation of CVE-2021-36833 in the wild and no public exploit code.

## Other vulnerabilities in ibericode MC4WP: Mailchimp for WordPress

- [CVE-2017-18577](https://insights.sbomify.com/CVE-2017-18577/): Cross-site scripting in n/a (medium 6.1)
- [CVE-2016-10871](https://insights.sbomify.com/CVE-2016-10871/): Cross-site scripting in n/a (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-36833 and fix it if it is affected.

What it is: CVE-2021-36833 is a medium-severity cross-site scripting vulnerability in ibericode MC4WP: Mailchimp for WordPress, published on 20 May 2022. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-36833 in the wild and no public exploit code.

Affected product: ibericode MC4WP: Mailchimp for WordPress. 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-2021-36833/ (Markdown: https://insights.sbomify.com/CVE-2021-36833/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-36833
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-36833
- OSV: https://osv.dev/vulnerability/CVE-2021-36833

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-36833/
Summaries are generated and may contain mistakes; the official description above is the record.