# CVE-2021-40109: Server-side request forgery in n/a

> Attackers with upload permissions can exploit SSRF to access internal network resources and upload disallowed file types via URL redirects.

- **Severity:** Medium 6.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Sep 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-mm62-vxgq-v5v9

## What is CVE-2021-40109?

CVE-2021-40109 is a medium-severity server-side request forgery vulnerability in Concretecms Concrete Cms, published on 27 Sep 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A SSRF issue was discovered in Concrete CMS through 8.5.5. Users can access forbidden files on their local network. A user with permissions to upload files from external sites can upload a URL that redirects to an internal resource of any file type. The redirect is followed and loads the contents of the file from the redirected-to server. Files of disallowed types can be uploaded.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2021-40109?

It affects 1 product.


Products: Concretecms Concrete Cms.

## How do I fix CVE-2021-40109?

No fix has been published for CVE-2021-40109 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-40109 being exploited?

There is no known exploitation of CVE-2021-40109 in the wild and no public exploit code.

## Other vulnerabilities in Concretecms Concrete Cms

- [CVE-2023-48648](https://insights.sbomify.com/CVE-2023-48648/): Concrete CMS allows unauthorized access because directories can be created with insecure permissions (critical 9.8)
- [CVE-2022-21829](https://insights.sbomify.com/CVE-2022-21829/): Code injection in concrete CMS (critical 9.8)
- [CVE-2021-22958](https://insights.sbomify.com/CVE-2021-22958/): Server-Side Request Forgery vulnerability in concrete5 (critical 9.8)
- [CVE-2021-40098](https://insights.sbomify.com/CVE-2021-40098/): Path traversal in n/a (critical 9.8)
- [CVE-2026-8134](https://insights.sbomify.com/CVE-2026-8134/): Concrete CMS Vulnerable to Relative Path Traversal (critical 9.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-40109 and fix it if it is affected.

What it is: CVE-2021-40109 is a medium-severity server-side request forgery vulnerability in Concretecms Concrete Cms, published on 27 Sep 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-40109 in the wild and no public exploit code.

Affected product: Concretecms Concrete Cms. 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-2021-40109/ (Markdown: https://insights.sbomify.com/CVE-2021-40109/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-40109
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-40109
- OSV: https://osv.dev/vulnerability/CVE-2021-40109

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-40109/
Summaries are generated and may contain mistakes; the official description above is the record.