# CVE-2021-31933: File upload in n/a

> Remote authenticated administrators can upload malicious PHP files via improper extension filtering and directory traversal to execute arbitrary code.

- **Severity:** High 7.2 (`CVSS:3.1/AC:L/AV:N/A:H/C:H/I:H/PR:H/S:U/UI:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 30 Apr 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-ch7w-rg8w-hgcj

## What is CVE-2021-31933?

CVE-2021-31933 is a high-severity vulnerability in n/a, published on 30 Apr 2021. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A remote code execution vulnerability exists in Chamilo through 1.11.14 due to improper input sanitization of a parameter used for file uploads, and improper file-extension filtering for certain filenames (e.g., .phar or .pht). A remote authenticated administrator is able to upload a file containing arbitrary PHP code into specific directories via main/inc/lib/fileUpload.lib.php directory traversal to achieve PHP code execution.

Weakness: CWE-706 (Use of Incorrectly-Resolved Name or Reference)

## Which versions are affected by CVE-2021-31933?

It affects 1 product.


Products: Chamilo Chamilo.

## How do I fix CVE-2021-31933?

No fix has been published for CVE-2021-31933 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-31933 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-31933 exists.

Public exploit code:

- Chamilo LMS 1.11.14 - Remote Code Execution (Authenticated) (exploitdb)

## Other vulnerabilities in n/a

- [CVE-2023-3368](https://insights.sbomify.com/CVE-2023-3368/): Chamilo LMS Unauthenticated Command Injection (critical 9.8)
- [CVE-2023-3533](https://insights.sbomify.com/CVE-2023-3533/): Chamilo LMS Unauthenticated Remote Code Execution via Arbitrary File Write (critical 9.8)
- [CVE-2023-3545](https://insights.sbomify.com/CVE-2023-3545/): Chamilo LMS Htaccess File Upload Security Bypass (critical 9.8)
- [CVE-2023-34960](https://insights.sbomify.com/CVE-2023-34960/): Command injection in n/a (critical 9.8)
- [CVE-2021-34187](https://insights.sbomify.com/CVE-2021-34187/): SQL injection in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-31933 and fix it if it is affected.

What it is: CVE-2021-31933 is a high-severity vulnerability in n/a, published on 30 Apr 2021. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-31933 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-2021-31933/ (Markdown: https://insights.sbomify.com/CVE-2021-31933/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-31933
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-31933
- OSV: https://osv.dev/vulnerability/CVE-2021-31933

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-31933/
Summaries are generated and may contain mistakes; the official description above is the record.