# CVE-2020-9757: SEOmatic for CraftCMS allows Server-Side Template Injection

> Attackers can execute arbitrary code via Server-Side Template Injection in the SEOmatic plugin for Craft CMS.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Mar 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-6q4j-8pjm-5mgc

## What is CVE-2020-9757?

CVE-2020-9757 is a critical code injection vulnerability in Craftcms Craft Cms, published on 4 Mar 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The SEOmatic component before 3.3.0 for Craft CMS allows Server-Side Template Injection that leads to RCE via malformed data to the metacontainers controller.

Weakness: CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component)

## Which versions are affected by CVE-2020-9757?

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 | 3.3.0 |
| `nystudio107/craft-seomatic` | Packagist | All versions | 3.3.0 |

Products: Craftcms Craft Cms.

## How do I fix CVE-2020-9757?

Upgrade nystudio107/craft-seomatic to 3.3.0 or later.

## Is CVE-2020-9757 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-9757 exists.

Public exploit code:

- Craft CMS < 3.3.0 - Server-Side Template Injection (nuclei): http/cves/2020/CVE-2020-9757.yaml

## Other vulnerabilities in Craftcms Craft Cms

- [CVE-2025-32432](https://insights.sbomify.com/CVE-2025-32432/): Craft CMS Code Injection (critical 10.0, exploited in the wild)
- [CVE-2024-56145](https://insights.sbomify.com/CVE-2024-56145/): Craft CMS Code Injection (critical 9.3, exploited in the wild)
- [CVE-2025-23209](https://insights.sbomify.com/CVE-2025-23209/): Craft CMS Code Injection (high 8.1, exploited in the wild)
- [CVE-2025-35939](https://insights.sbomify.com/CVE-2025-35939/): Craft CMS External Control of Assumed-Immutable Web Parameter (medium 6.9, exploited in the wild)
- [CVE-2023-41892](https://insights.sbomify.com/CVE-2023-41892/): Craft CMS Remote Code Execution vulnerability (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-9757 and fix it if it is affected.

What it is: CVE-2020-9757 is a critical code injection vulnerability in Craftcms Craft Cms, published on 4 Mar 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-9757 exists.

Affected packages and fixed versions:
- nystudio107/craft-seomatic (Packagist): affected all versions; fixed in 3.3.0
- nystudio107/craft-seomatic (Packagist): affected all versions; fixed in 3.3.0

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-2020-9757/ (Markdown: https://insights.sbomify.com/CVE-2020-9757/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-9757
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-9757
- OSV: https://osv.dev/vulnerability/CVE-2020-9757

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-9757/
Summaries are generated and may contain mistakes; the official description above is the record.