# CVE-2013-4939: Cross-Site Scripting in yui

> Remote attackers can inject arbitrary web script or HTML via crafted URLs in the YUI IO Utility component, affecting applications like Moodle.

- **Severity:** Medium 4.3 (`AV:N/AC:M/Au:N/C:N/I:P/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:** 26 Jul 2013
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-mj87-8xf8-fp4w

## What is CVE-2013-4939?

CVE-2013-4939 is a medium-severity cross-site scripting vulnerability in Moodle Moodle, published on 26 Jul 2013. 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

Cross-site scripting (XSS) vulnerability in io.swf in the IO Utility component in Yahoo! YUI 3.0.0 through 3.9.1, as used in Moodle through 2.1.10, 2.2.x before 2.2.11, 2.3.x before 2.3.8, 2.4.x before 2.4.5, 2.5.x before 2.5.1, and other products, allows remote attackers to inject arbitrary web script or HTML via a crafted string in a URL.

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

## Which versions are affected by CVE-2013-4939?

2 open source packages ship an affected version, including yui. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `yui` | npm | All versions | 3.10.3 |
| `yui` | npm | All versions | 3.10.3 |

Products: Moodle Moodle, Yahoo Yui.

## How do I fix CVE-2013-4939?

Upgrade yui to 3.10.3 or later.

## Is CVE-2013-4939 being exploited?

There is no known exploitation of CVE-2013-4939 in the wild and no public exploit code.

## Other vulnerabilities in Moodle Moodle

- [CVE-2006-4935](https://insights.sbomify.com/CVE-2006-4935/): File upload in n/a (critical 10.0)
- [CVE-2006-4936](https://insights.sbomify.com/CVE-2006-4936/): Moodle does not properly validate module instance id (critical 10.0)
- [CVE-2004-2233](https://insights.sbomify.com/CVE-2004-2233/): Unknown "front page vulnerability with Moodle servers" for Moodle before 1.3.2 has unknown impact and attack vectors. (critical 10.0)
- [CVE-2004-2235](https://insights.sbomify.com/CVE-2004-2235/): Cross-site scripting in n/a (critical 10.0)
- [CVE-2004-2236](https://insights.sbomify.com/CVE-2004-2236/): Other in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2013-4939 and fix it if it is affected.

What it is: CVE-2013-4939 is a medium-severity cross-site scripting vulnerability in Moodle Moodle, published on 26 Jul 2013. 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-2013-4939 in the wild and no public exploit code.

Affected packages and fixed versions:
- yui (npm): affected all versions; fixed in 3.10.3
- yui (npm): affected all versions; fixed in 3.10.3

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-2013-4939/ (Markdown: https://insights.sbomify.com/CVE-2013-4939/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2013-4939
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2013-4939
- OSV: https://osv.dev/vulnerability/CVE-2013-4939

---
From sbomify Insights: https://insights.sbomify.com/CVE-2013-4939/
Summaries are generated and may contain mistakes; the official description above is the record.