# GHSA-mf74-qq7w-6j7v: Zmarkdown Server-Side Request Forgery (SSRF) in remark-download-images

> An attacker can exploit loose URL filtering to access private network resources via Server-Side Request Forgery in the remark-download-images library.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 3 Feb 2024

## What is GHSA-mf74-qq7w-6j7v?

GHSA-mf74-qq7w-6j7v is a server-side request forgery vulnerability in remark-images-download, published on 3 Feb 2024. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

### Impact

A major blind SSRF has been found in `remark-images-download`, which allowed
for requests to be made to neighboring servers on local IP ranges.
The issue came from a loose filtering of URLs inside the module.

Imagine a server running on a private network `192.168.1.0/24`.
A private service serving images is running on `192.168.1.2`, and
is not expected to be accessed by users. A machine is running
`remark-images-download` on the neighboring `192.168.1.3` host.
An user enters the following Markdown:

```markdown
![](http://192.168.1.2/private-img.png)
```

The image is downloaded by the server and included inside the resulting
document. Hence, the user has access to the private image.

It has been corrected by preventing images downloads from
local IP ranges, both in IPv4 and IPv6.
To avoid malicious domain names, resolved local IPs from are also
forbidden inside the module.
This vulnerability impact is moderate, as it is can allow access to
unexposed documents on the local network, and is very easy
to exploit.

### Patches

The vulnerability has been patched in version 3.1.0.
If impacted, you should update to this version as soon as possible.

Please note that a minor version has been released instead of a bugfix.
This is due to a new option included to prevent another vulnerability,
upgrading to the new version will not break compatibility.

### Workarounds

No workaround is known, the package should be upgraded.

### For more information

If you have any questions or comments about this advisory, open an issue in [ZMarkdown](https://github.com/zestedesavoir/zmarkdown/issues).

## Which versions are affected by GHSA-mf74-qq7w-6j7v?

2 open source packages ship an affected version, including remark-images-download.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `remark-images-download` | npm | All versions | 3.1.0 |
| `remark-images-download` | npm | All versions | 3.1.0 |

## How do I fix GHSA-mf74-qq7w-6j7v?

Upgrade remark-images-download to 3.1.0 or later.

## Is GHSA-mf74-qq7w-6j7v being exploited?

There is no known exploitation of GHSA-mf74-qq7w-6j7v in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-mf74-qq7w-6j7v and fix it if it is affected.

What it is: GHSA-mf74-qq7w-6j7v is a server-side request forgery vulnerability in remark-images-download, published on 3 Feb 2024. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of GHSA-mf74-qq7w-6j7v in the wild and no public exploit code.

Affected packages and fixed versions:
- remark-images-download (npm): affected all versions; fixed in 3.1.0
- remark-images-download (npm): affected all versions; fixed in 3.1.0

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/GHSA-mf74-qq7w-6j7v/ (Markdown: https://insights.sbomify.com/GHSA-mf74-qq7w-6j7v/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-mf74-qq7w-6j7v

---
From sbomify Insights: https://insights.sbomify.com/GHSA-mf74-qq7w-6j7v/
Summaries are generated and may contain mistakes; the official description above is the record.