SSRF in Bigbluebutton
CVE-2023-33176
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.
Vulnerability class: SSRF (Server-Side Request Forgery)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L.
EPSS exploit prediction
EPSS: 0.005 (38.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 38.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Bigbluebutton — versions >= 2.6.0, < 2.6.9, < 2.5.18
Weakness classification (CWE)
References
- github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-3q22-hph2-cff7 (Vendor Advisory)
- github.com/bigbluebutton/bigbluebutton/pull/18045 (Patch)
- github.com/bigbluebutton/bigbluebutton/pull/18052 (Issue Tracking)
- github.com/bigbluebutton/bigbluebutton/commit/43394dade595d0707384e487835790153… (Patch)
- github.com/bigbluebutton/bigbluebutton/commit/b18aff32e65a47f1eb2c800e86dcfc7a8… (Patch)
Frequently asked questions
- What is CVE-2023-33176?
- CVE-2023-33176 is a medium-severity vulnerability in Bigbluebutton, classified under Server-Side Request Forgery (SSRF). CVSS score: 4.8/10. Published 2023-06-26.
- How severe is CVE-2023-33176?
- Medium severity. CVSS v3 base score is 4.8 out of 10.