# CVE-2021-20721: File upload in KonaWiki2

> Remote attackers can upload arbitrary files, potentially executing PHP code, affecting KonaWiki2 users.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 20 May 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-8438-2753-v3v3

## What is CVE-2021-20721?

CVE-2021-20721 is a critical vulnerability in kujirahand KonaWiki2, published on 20 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

KonaWiki2 versions prior to 2.2.4 allows a remote attacker to upload arbitrary files via unspecified vectors. If the file contains PHP scripts, arbitrary code may be executed.

Weakness: CWE-434 (Unrestricted Upload of File with Dangerous Type)

## Which versions are affected by CVE-2021-20721?

It affects 1 product.


Products: Kujirahand Konawiki.

## How do I fix CVE-2021-20721?

No fix has been published for CVE-2021-20721 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-20721 being exploited?

There is no known exploitation of CVE-2021-20721 in the wild and no public exploit code.

## Other vulnerabilities in kujirahand KonaWiki2

- [CVE-2021-20720](https://insights.sbomify.com/CVE-2021-20720/): SQL injection in KonaWiki2 (critical 9.8)
- [CVE-2020-5612](https://insights.sbomify.com/CVE-2020-5612/): Cross-site scripting in KonaWiki (medium 6.1)
- [CVE-2020-5613](https://insights.sbomify.com/CVE-2020-5613/): Cross-site scripting in KonaWiki (medium 6.1)
- [CVE-2020-5614](https://insights.sbomify.com/CVE-2020-5614/): Path traversal in KonaWiki (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20721 and fix it if it is affected.

What it is: CVE-2021-20721 is a critical vulnerability in kujirahand KonaWiki2, published on 20 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-20721 in the wild and no public exploit code.

Affected product: kujirahand KonaWiki2. 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-2021-20721/ (Markdown: https://insights.sbomify.com/CVE-2021-20721/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20721
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20721
- OSV: https://osv.dev/vulnerability/CVE-2021-20721

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20721/
Summaries are generated and may contain mistakes; the official description above is the record.