# GHSA-xcxh-6cv4-q8p8: HFS user adding a "web link" in HFS is vulnerable to "target=_blank" exploit

> An attacker can hijack the HFS admin tab via a malicious web link, potentially leading to credential theft through phishing.

- **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:** 12 Aug 2025

## What is GHSA-xcxh-6cv4-q8p8?

GHSA-xcxh-6cv4-q8p8 is a vulnerability in hfs, published on 12 Aug 2025. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

### Summary
When adding a "web link" to the HFS virtual filesystem, the frontend opens it with `target="_blank"` but without the `rel="noopener noreferrer"` attribute. This allows the opened page to use the `window.opener` property to change the location of the original HFS tab.

### Details
While most modern browsers have fixes already implemented for this `target="_blank"` exploit at the browser level, users on outdated browsers remain vulnerable. This means that if an admin of the HFS instance adds a link to an external third-party service (that they believe is safe at the time) and that service they added later becomes compromised, the malicious page could replace the original HFS tab's content with a phishing page. This does not require the admin account itself to be compromised, only that a legitimate linked site turns malicious.

### Impact
Affected users (people using old browsers without the browser level fix) could be misled into entering their HFS credentials or other sensitive information into a fake site controlled by an attacker. This vulnerability is fixed in most modern browsers, but adding `rel="noopener noreferrer"` remains a best practice to protect legacy environments.

### PoC

Firstly, in the HFS admin page, under the filesystem (/~/admin/#/fs) press "Add" then "web link" then set the link to take the user to to an HTML file that exploits this vulnerability, here is an example of a malicious HTML file's code:

```<html>
 <body>
  <script>
    window.opener.location = "https://example.org";
  </script>
<b>Error loading...</b>
 </body>
</html>
```

Now, in the HFS folder you placed this web link in, open HFS and click the web link, if you aren't on a modern browser that fixed this vulnerability on the browser level, then switch back to the HFS tab that opened it, and you should be taken to "https://example.org" if you tried the code I provided, or whatever other page you tried.

## Which versions are affected by GHSA-xcxh-6cv4-q8p8?

2 open source packages ship an affected version, including hfs.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `hfs` | npm | All versions | 0.57.10 |
| `hfs` | npm | All versions | 0.57.10 |

## How do I fix GHSA-xcxh-6cv4-q8p8?

Upgrade hfs to 0.57.10 or later.

## Is GHSA-xcxh-6cv4-q8p8 being exploited?

There is no known exploitation of GHSA-xcxh-6cv4-q8p8 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-xcxh-6cv4-q8p8 and fix it if it is affected.

What it is: GHSA-xcxh-6cv4-q8p8 is a vulnerability in hfs, published on 12 Aug 2025. 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-xcxh-6cv4-q8p8 in the wild and no public exploit code.

Affected packages and fixed versions:
- hfs (npm): affected all versions; fixed in 0.57.10
- hfs (npm): affected all versions; fixed in 0.57.10

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-xcxh-6cv4-q8p8/ (Markdown: https://insights.sbomify.com/GHSA-xcxh-6cv4-q8p8/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-xcxh-6cv4-q8p8

---
From sbomify Insights: https://insights.sbomify.com/GHSA-xcxh-6cv4-q8p8/
Summaries are generated and may contain mistakes; the official description above is the record.