# CVE-2023-33176: Blind SSRF When Uploading Presentation in BigBlueButton

> Attackers can exploit a blind SSRF vulnerability in BigBlueButton's document upload feature to force the server to make arbitrary requests.

- **Severity:** Medium 4.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 Jun 2023
- **Updated:** 12 Nov 2024
- **Also known as:** GHSA-3q22-hph2-cff7

## What is CVE-2023-33176?

CVE-2023-33176 is a medium-severity server-side request forgery vulnerability in bigbluebutton, published on 26 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

BigBlueButton is an open source virtual classroom designed to help teachers teach and learners learn. In affected versions are affected by a Server-Side Request Forgery (SSRF) vulnerability. In an `insertDocument` API request the user is able to supply a URL from which the presentation should be downloaded. This URL was being used without having been successfully validated first. An update to the `followRedirect` method in the `PresentationUrlDownloadService` has been made to validate all URLs to be used for presentation download. Two new properties `presentationDownloadSupportedProtocols` and `presentationDownloadBlockedHosts` have also been added to `bigbluebutton.properties` to allow administrators to define what protocols a URL must use and to explicitly define hosts that a presentation cannot be downloaded from. All URLs passed to `insertDocument` must conform to the requirements of the two previously mentioned properties. Additionally, these URLs must resolve to valid addresses, and these addresses must not be local or loopback addresses. There are no workarounds. Users are advised to upgrade to a patched version of BigBlueButton.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2023-33176?

It affects 1 product.


Products: Bigbluebutton Bigbluebutton.

## How do I fix CVE-2023-33176?

No fix has been published for CVE-2023-33176 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-33176 being exploited?

There is no known exploitation of CVE-2023-33176 in the wild and no public exploit code.

## Other vulnerabilities in bigbluebutton

- [CVE-2020-27602](https://insights.sbomify.com/CVE-2020-27602/): Other in n/a (critical 9.8)
- [CVE-2020-27605](https://insights.sbomify.com/CVE-2020-27605/): Code injection in n/a (critical 9.8)
- [CVE-2020-12443](https://insights.sbomify.com/CVE-2020-12443/): Path traversal in n/a (critical 9.8)
- [CVE-2020-27613](https://insights.sbomify.com/CVE-2020-27613/): Hardcoded credentials in n/a (high 8.4)
- [CVE-2021-4143](https://insights.sbomify.com/CVE-2021-4143/): Cross-site Scripting (XSS) - Generic in bigbluebutton/bigbluebutton (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-33176 and fix it if it is affected.

What it is: CVE-2023-33176 is a medium-severity server-side request forgery vulnerability in bigbluebutton, published on 26 Jun 2023. 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-2023-33176 in the wild and no public exploit code.

Affected product: bigbluebutton. 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-2023-33176/ (Markdown: https://insights.sbomify.com/CVE-2023-33176/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-33176
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-33176
- OSV: https://osv.dev/vulnerability/CVE-2023-33176

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-33176/
Summaries are generated and may contain mistakes; the official description above is the record.