CVE-2023-33176
MediumCVSS 4.8Exploitation Probability (EPSS)
Low risk30th percentile - higher than 30% of all known CVEs
Summary
BigBlueButton, an open-source virtual classroom, has a Server-Side Request Forgery (SSRF) vulnerability in affected versions that allows users to supply a URL for downloading presentations without prior validation. An update to the `followRedirect` method has been made to validate all URLs used for presentation downloads.
Risk Assessment
This vulnerability could lead to unauthorized access to internal organizational resources, posing a serious threat to data security. The lack of proper safeguards may allow attackers to exploit this flaw to conduct attacks on network infrastructure.
Recommendation
It is recommended to upgrade to a patched version of BigBlueButton to implement the new URL validation properties. Administrators should also configure `presentationDownloadSupportedProtocols` and `presentationDownloadBlockedHosts` in the `bigbluebutton.properties` file.
Original NVD description (English source)
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.