# CVE-2023-28439: ckeditor4 plugins vulnerable to cross-site scripting caused by the editor instance destroying process

> Attackers can execute arbitrary JavaScript via XSS in CKEditor4 when specific initialization and destruction conditions are met without proper CSP.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/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:** Yes
- **Published:** 22 Mar 2023
- **Updated:** 13 Feb 2025
- **Also known as:** DEBIAN-CVE-2023-28439, GHSA-vh5c-xwqv-cv9g, UBUNTU-CVE-2023-28439

## What is CVE-2023-28439?

CVE-2023-28439 is a medium-severity cross-site scripting vulnerability in Fedoraproject Fedora, published on 22 Mar 2023. 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

CKEditor4 is an open source what-you-see-is-what-you-get HTML editor. A cross-site scripting vulnerability has been discovered affecting Iframe Dialog and Media Embed packages. The vulnerability may trigger a JavaScript code after fulfilling special conditions: using one of the affected packages on a web page with missing proper Content Security Policy configuration; initializing the editor on an element and using an element other than `<textarea>` as a base; and destroying the editor instance. This vulnerability might affect a small percentage of integrators that depend on dynamic editor initialization/destroy mechanism.

A fix is available in CKEditor4 version 4.21.0. In some rare cases, a security fix may be considered a breaking change. Starting from version 4.21.0, the Iframe Dialog plugin applies the `sandbox` attribute by default, which restricts JavaScript code execution in the iframe element. To change this behavior, configure the `config.iframe_attributes` option. Also starting from version 4.21.0, the Media Embed plugin regenerates the entire content of the embed widget by default. To change this behavior, configure the `config.embed_keepOriginalContent` option. Those who choose to enable either of the more permissive options or who cannot upgrade to a patched version should properly configure Content Security Policy to avoid any potential security issues that may arise from embedding iframe elements on their web page.

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

## Which versions are affected by CVE-2023-28439?

It affects 2 products.


Products: Ckeditor Ckeditor, Fedoraproject Fedora.

## How do I fix CVE-2023-28439?

Upgrade to a fixed version.

## Is CVE-2023-28439 being exploited?

There is no known exploitation of CVE-2023-28439 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2023-31541](https://insights.sbomify.com/CVE-2023-31541/): File upload in n/a (critical 9.8)
- [CVE-2021-41164](https://insights.sbomify.com/CVE-2021-41164/): Advanced Content Filter (ACF) vulnerability allowing to execute JavaScript code using malformed HTML (high 8.2)
- [CVE-2021-41165](https://insights.sbomify.com/CVE-2021-41165/): HTML comments vulnerability allowing to execute JavaScript code (high 8.2)
- [CVE-2021-32808](https://insights.sbomify.com/CVE-2021-32808/): Cross-site scripting in ckeditor via abuse of undo functionality (high 7.6)
- [CVE-2011-4972](https://insights.sbomify.com/CVE-2011-4972/): Missing authorization in CKEditor Drupal module (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-28439 and fix it if it is affected.

What it is: CVE-2023-28439 is a medium-severity cross-site scripting vulnerability in Fedoraproject Fedora, published on 22 Mar 2023. 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-2023-28439 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-2023-28439/ (Markdown: https://insights.sbomify.com/CVE-2023-28439/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-28439
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-28439
- OSV: https://osv.dev/vulnerability/CVE-2023-28439

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-28439/
Summaries are generated and may contain mistakes; the official description above is the record.