# CVE-2021-46387: Cross-site scripting in n/a

> An attacker can execute arbitrary JavaScript via insecure URI handling in ZyXEL ZyWALL appliances, enabling session hijacking and clipboard attacks.

- **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:** No
- **Published:** 1 Mar 2022
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-f4h9-4w7g-w29c

## What is CVE-2021-46387?

CVE-2021-46387 is a medium-severity cross-site scripting vulnerability in n/a, published on 1 Mar 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

ZyXEL ZyWALL 2 Plus Internet Security Appliance is affected by Cross Site Scripting (XSS). Insecure URI handling leads to bypass security restriction to achieve Cross Site Scripting, which allows an attacker able to execute arbitrary JavaScript codes to perform multiple attacks such as clipboard hijacking and session hijacking.

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

## Which versions are affected by CVE-2021-46387?

It affects 1 product.


Products: Zyxel Zywall 2 Plus Internet Security Appliance Firmware.

## How do I fix CVE-2021-46387?

No fix has been published for CVE-2021-46387 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-46387 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-46387 exists.

Public exploit code:

- Zyxel ZyWALL 2 Plus Internet Security Appliance - Cross-Site Scripting (XSS) (exploitdb)
- Zyxel ZyWALL 2 Plus Internet Security Appliance - Cross-Site Scripting (nuclei): http/cves/2021/CVE-2021-46387.yaml

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-46387 and fix it if it is affected.

What it is: CVE-2021-46387 is a medium-severity cross-site scripting vulnerability in n/a, published on 1 Mar 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-46387 exists.

Affected product: n/a. 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-2021-46387/ (Markdown: https://insights.sbomify.com/CVE-2021-46387/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-46387
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-46387
- OSV: https://osv.dev/vulnerability/CVE-2021-46387

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-46387/
Summaries are generated and may contain mistakes; the official description above is the record.