# CVE-2021-23838: Cross-site scripting in n/a

> Reflected XSS in flatCore allows attackers to steal cookies and hijack sessions via the media_filter parameter in the admin interface.

- **Severity:** Medium 4.8 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 15 Jan 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-w58h-cm85-98cc

## What is CVE-2021-23838?

CVE-2021-23838 is a medium-severity cross-site scripting vulnerability in n/a, published on 15 Jan 2021. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

An issue was discovered in flatCore before 2.0.0 build 139. A reflected XSS vulnerability was identified in the media_filter HTTP request body parameter for the acp interface. The affected parameter accepts malicious client-side script without proper input sanitization. For example, a malicious user can leverage this vulnerability to steal cookies from a victim user and perform a session-hijacking attack, which may then lead to unauthorized access to the site.

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

## Which versions are affected by CVE-2021-23838?

It affects 1 product.


Products: Flatcore Flatcore.

## How do I fix CVE-2021-23838?

No fix has been published for CVE-2021-23838 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-23838 being exploited?

There is no known exploitation of CVE-2021-23838 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2019-13961](https://insights.sbomify.com/CVE-2019-13961/): Cross-site request forgery in n/a (high 8.8)
- [CVE-2020-17452](https://insights.sbomify.com/CVE-2020-17452/): File upload in n/a (high 7.2)
- [CVE-2019-10652](https://insights.sbomify.com/CVE-2019-10652/): File upload in n/a (high 7.2)
- [CVE-2021-23837](https://insights.sbomify.com/CVE-2021-23837/): SQL injection in n/a (medium 6.5)
- [CVE-2017-9451](https://insights.sbomify.com/CVE-2017-9451/): Cross-site scripting in n/a (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-23838 and fix it if it is affected.

What it is: CVE-2021-23838 is a medium-severity cross-site scripting vulnerability in n/a, published on 15 Jan 2021. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-23838 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-2021-23838/ (Markdown: https://insights.sbomify.com/CVE-2021-23838/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-23838
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-23838
- OSV: https://osv.dev/vulnerability/CVE-2021-23838

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-23838/
Summaries are generated and may contain mistakes; the official description above is the record.