# CVE-2021-32478: Moodle reflected XSS

> Attackers can exploit unsanitized redirect URIs in Moodle's LTI endpoint to perform reflected XSS and open redirects, potentially compromising user sessions.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/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:** 11 Mar 2022
- **Updated:** 3 Aug 2024
- **Also known as:** BIT-moodle-2021-32478, GHSA-78fm-qhh8-8858, UBUNTU-CVE-2021-32478

## What is CVE-2021-32478?

CVE-2021-32478 is a medium-severity cross-site scripting vulnerability in Moodle Moodle, published on 11 Mar 2022. 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

The redirect URI in the LTI authorization endpoint required extra sanitizing to prevent reflected XSS and open redirect risks. Moodle versions 3.10 to 3.10.3, 3.9 to 3.9.6, 3.8 to 3.8.8 and earlier unsupported versions are affected.

Weakness: CWE-601 (URL Redirection to Untrusted Site), CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2021-32478?

7 open source packages ship an affected version, including moodle/moodle and moodle. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `moodle/moodle` | Packagist | From 3.10 | 3.10.4 |
| `moodle/moodle` | Packagist | From 3.10 | 3.10.4 |
| `moodle/moodle` | Packagist | From 3.8 | 3.8.9 |
| `moodle/moodle` | Packagist | From 3.8 | 3.8.9 |
| `moodle/moodle` | Packagist | From 3.9 | 3.9.7 |
| `moodle/moodle` | Packagist | From 3.9 | 3.9.7 |
| `moodle` | Bitnami | All versions | 3.8.9, 3.9.7, 3.10.4 |

Products: Moodle Moodle.

## How do I fix CVE-2021-32478?

Upgrade moodle/moodle to a fixed version for your release line: 3.10.4, 3.8.9 or 3.9.7.

## Is CVE-2021-32478 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-32478 exists.

Public exploit code:

- Moodle 3.8-3.10.3 - Reflected XSS & Open Redirect (nuclei): http/cves/2021/CVE-2021-32478.yaml

## 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-2021-32478 and fix it if it is affected.

What it is: CVE-2021-32478 is a medium-severity cross-site scripting vulnerability in Moodle Moodle, published on 11 Mar 2022. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-32478 exists.

Affected packages and fixed versions:
- moodle/moodle (Packagist): affected from 3.10; fixed in 3.10.4
- moodle/moodle (Packagist): affected from 3.10; fixed in 3.10.4
- moodle/moodle (Packagist): affected from 3.8; fixed in 3.8.9
- moodle/moodle (Packagist): affected from 3.8; fixed in 3.8.9
- moodle/moodle (Packagist): affected from 3.9; fixed in 3.9.7
- moodle/moodle (Packagist): affected from 3.9; fixed in 3.9.7
- moodle (Bitnami): affected all versions; fixed in 3.8.9, 3.9.7, 3.10.4

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-2021-32478/ (Markdown: https://insights.sbomify.com/CVE-2021-32478/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32478
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32478
- OSV: https://osv.dev/vulnerability/CVE-2021-32478

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32478/
Summaries are generated and may contain mistakes; the official description above is the record.