CVE-2025-61601 in BigBlueButton
Summary
by MITRE • 10/10/2025
BigBlueButton is an open-source virtual classroom. A Denial of Service (DoS) vulnerability in versions prior to 3.0.13 allows any authenticated user to freeze or crash the entire server by abusing the polling feature's `Choices` response type. By submitting a malicious payload with a massive array in the `answerIds` field, the attacker can cause the current meeting — and potentially all meetings on the server — to become unresponsive. Version 3.0.13 contains a patch. No known workarounds are available.
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Analysis
by VulDB Data Team • 10/10/2025
The vulnerability identified as CVE-2025-61601 affects BigBlueButton version 3.0.13 and earlier, representing a critical denial of service flaw that undermines the stability and availability of virtual classroom environments. This vulnerability specifically targets the polling feature's response handling mechanism, where authenticated users can exploit a design flaw in the `Choices` response type to disrupt system operations. The flaw stems from insufficient input validation and sanitization within the server's processing pipeline for poll responses, creating a pathway for malicious actors to cause cascading failures across meeting sessions.
The technical exploitation involves crafting a malicious payload that includes an extraordinarily large array within the `answerIds` field of the polling response. This malformed data triggers a resource exhaustion condition within the server's processing logic, causing the targeted meeting session to freeze or crash entirely. The vulnerability's impact extends beyond individual meetings as the flawed response handling can potentially propagate across the entire server infrastructure, affecting all active sessions simultaneously. The vulnerability manifests through improper handling of array-based data structures in the server's backend processing, where recursive or iterative operations on oversized data arrays consume excessive CPU cycles and memory resources.
From an operational perspective, this vulnerability represents a significant threat to educational institutions and organizations relying on BigBlueButton for virtual learning environments. The ability for any authenticated user to cause widespread service disruption undermines the platform's reliability and availability guarantees. The vulnerability's exploitation does not require advanced technical skills or privileged access beyond standard user authentication, making it particularly dangerous in environments where user access controls may be less stringent. Security teams face the challenge of monitoring and detecting such attacks while maintaining service availability for legitimate users.
The vulnerability aligns with CWE-400, which addresses "Uncontrolled Resource Consumption," and reflects patterns commonly found in denial of service attacks targeting array processing and data structure handling. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, "Endpoint Denial of Service," and demonstrates how authenticated access can be leveraged to cause system-wide disruptions. Organizations should prioritize immediate patch deployment to version 3.0.13 or later, as no effective workarounds exist for this specific flaw. The vulnerability highlights the importance of input validation and resource management in multi-user environments where malicious actors can exploit legitimate features to cause service degradation. Security monitoring should focus on unusual patterns in polling activity and resource consumption spikes that may indicate exploitation attempts.