CVE-2020-25902 in Collaborate Ultra
Summary
by MITRE • 03/03/2021
Blackboard Collaborate Ultra 20.02 is affected by a cross-site scripting (XSS) vulnerability. The XSS payload will execute on the class room, which leads to stealing cookies from users who join the class.
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Analysis
by VulDB Data Team • 05/04/2025
Blackboard Collaborate Ultra version 20.02 contains a critical cross-site scripting vulnerability that allows remote attackers to execute malicious scripts within the context of user sessions. This vulnerability exists due to insufficient input validation and output encoding mechanisms within the web application's handling of user-supplied data. The flaw specifically manifests when the application fails to properly sanitize user inputs that are subsequently rendered in web pages without adequate escaping or encoding, creating an environment where malicious scripts can be injected and executed.
The technical implementation of this vulnerability enables attackers to craft specially formatted payloads that, when processed by the application, get executed in the browser context of authenticated users. When users join virtual classrooms, any malicious script injected through this vulnerability will execute within their browser session, potentially allowing attackers to access sensitive session cookies, user credentials, or other session-related data. The XSS payload can be delivered through various vectors including chat messages, user profile information, or classroom parameters that are not properly sanitized before rendering.
The operational impact of this vulnerability is significant as it compromises the security of the entire collaborative learning environment. Attackers can leverage this weakness to perform session hijacking attacks, where they steal authentication cookies and impersonate legitimate users to gain unauthorized access to classroom sessions, shared resources, and user data. This vulnerability undermines the fundamental security assumptions of the platform, as it allows attackers to execute code in the context of any user's browser, potentially leading to complete account compromise and unauthorized access to educational materials. The attack can be executed without requiring any special privileges or authentication from the attacker's side.
This vulnerability maps to CWE-79 Cross-site Scripting and aligns with ATT&CK technique T1531 Credential Access through Web Protocols, specifically targeting session management and credential theft. Organizations should implement comprehensive input validation and output encoding measures to prevent the execution of malicious scripts. The recommended mitigations include implementing strict content security policies, enforcing proper input sanitization for all user-supplied data, and deploying web application firewalls to detect and block malicious payloads. Additionally, regular security updates and patches should be applied promptly to address known vulnerabilities, and user education regarding suspicious activities should be maintained to reduce the risk of successful exploitation.