# CVE-2021-41750: Cross-site Scripting in SEOmatic plugin

> Remote attackers can inject arbitrary web script via crafted GET parameters in the SEOmatic plugin for Craft CMS.

- **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:** 12 Jun 2022
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-6hjc-m38h-7jhh

## What is CVE-2021-41750?

CVE-2021-41750 is a medium-severity cross-site scripting vulnerability in n/a, published on 12 Jun 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

A cross-site scripting (XSS) vulnerability in the SEOmatic plugin 3.4.10 for Craft CMS 3 allows remote attackers to inject arbitrary web script via a GET to /index.php?action=seomatic/file/seo-file-link with url parameter containing the base64 encoded URL of a malicious web page / file and fileName parameter containing an arbitrary filename with the intended content-type to be rendered in the user's browser as the extension.

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

## Which versions are affected by CVE-2021-41750?

2 open source packages ship an affected version, including nystudio107/craft-seomatic. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `nystudio107/craft-seomatic` | Packagist | All versions | 3.4.11 |
| `nystudio107/craft-seomatic` | Packagist | All versions | 3.4.11 |

Products: Nystudio107 Seomatic.

## How do I fix CVE-2021-41750?

Upgrade nystudio107/craft-seomatic to 3.4.11 or later.

## Is CVE-2021-41750 being exploited?

There is no known exploitation of CVE-2021-41750 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-41749](https://insights.sbomify.com/CVE-2021-41749/): Code Injection in SEOmatic (critical 9.8)
- [CVE-2021-44618](https://insights.sbomify.com/CVE-2021-44618/): Server-side Template Injection in nystudio107/craft-seomatic (critical 9.8)
- [CVE-2020-12790](https://insights.sbomify.com/CVE-2020-12790/): SEOmatic for CraftCMS allows Server-Side Template Injection (high 7.5)
- [CVE-2018-14716](https://insights.sbomify.com/CVE-2018-14716/): SEOmatic plugin for Craft CMS SSTI Vulnerability (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-41750 and fix it if it is affected.

What it is: CVE-2021-41750 is a medium-severity cross-site scripting vulnerability in n/a, published on 12 Jun 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: There is no known exploitation of CVE-2021-41750 in the wild and no public exploit code.

Affected packages and fixed versions:
- nystudio107/craft-seomatic (Packagist): affected all versions; fixed in 3.4.11
- nystudio107/craft-seomatic (Packagist): affected all versions; fixed in 3.4.11

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-2021-41750/ (Markdown: https://insights.sbomify.com/CVE-2021-41750/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-41750
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-41750
- OSV: https://osv.dev/vulnerability/CVE-2021-41750

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-41750/
Summaries are generated and may contain mistakes; the official description above is the record.