# CVE-2021-28001: Cross-site scripting in n/a

> Remote attackers can execute arbitrary code via a cross-site scripting vulnerability in the Comments parameter of Textpattern CMS.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/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:** A user has to click or open something
- **Fix available:** No
- **Published:** 19 Aug 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-36x9-48hm-r28q

## What is CVE-2021-28001?

CVE-2021-28001 is a medium-severity cross-site scripting vulnerability in n/a, published on 19 Aug 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

A cross-site scripting vulnerability was discovered in the Comments parameter in Textpattern CMS 4.8.4 which allows remote attackers to execute arbitrary code via a crafted payload entered into the URL field. The vulnerability is triggered by users visiting https://site.com/articles/welcome-to-your-site#comments-head.

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

## Which versions are affected by CVE-2021-28001?

It affects 1 product.


Products: Textpattern Textpattern.

## How do I fix CVE-2021-28001?

No fix has been published for CVE-2021-28001 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-28001 being exploited?

There is no known exploitation of CVE-2021-28001 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-19510](https://insights.sbomify.com/CVE-2020-19510/): File upload in n/a (critical 9.8)
- [CVE-2018-7474](https://insights.sbomify.com/CVE-2018-7474/): SQL injection in n/a (critical 9.8)
- [CVE-2023-50038](https://insights.sbomify.com/CVE-2023-50038/): File upload in n/a (high 8.8)
- [CVE-2023-24269](https://insights.sbomify.com/CVE-2023-24269/): File upload in n/a (high 8.8)
- [CVE-2020-29458](https://insights.sbomify.com/CVE-2020-29458/): Cross-site request forgery in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28001 and fix it if it is affected.

What it is: CVE-2021-28001 is a medium-severity cross-site scripting vulnerability in n/a, published on 19 Aug 2021. 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 CVE-2021-28001 in the wild and no public exploit code.

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-2021-28001/ (Markdown: https://insights.sbomify.com/CVE-2021-28001/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28001
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28001
- OSV: https://osv.dev/vulnerability/CVE-2021-28001

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28001/
Summaries are generated and may contain mistakes; the official description above is the record.