CVE-2022-41965 is a medium-severity vulnerability classified as CWE-601, an Open Redirect issue found in the Opencast platform prior to version 12.5. Opencast is an open-source system widely used for managing educational audio and video content, often deployed by universities and educational institutions. The vulnerability resides in the Paella authentication page component, which improperly handles URL redirection for authenticated users. Specifically, it allows an attacker to craft a URL that, when accessed by a logged-in user, redirects them to an arbitrary external website outside the legitimate Opencast domain. This open redirect flaw can be exploited to facilitate phishing attacks by tricking users into visiting malicious sites that may impersonate trusted services or harvest credentials. The vulnerability does not directly compromise the Opencast system's confidentiality, integrity, or availability but serves as a vector for social engineering and secondary attacks. The issue was addressed and fixed in Opencast version 12.5 and later. There are no known exploits in the wild reported to date, and exploitation requires the user to be authenticated and to interact with a maliciously crafted URL. Since the vulnerability affects only versions prior to 12.5, organizations running older versions remain at risk if they have not applied the update or mitigations.

For European organizations, particularly educational institutions and universities that rely on Opencast for managing and distributing educational media content, this vulnerability poses a risk primarily in the form of phishing and social engineering attacks. Attackers could leverage the open redirect to redirect authenticated users to malicious websites designed to steal credentials or deliver malware. This could lead to unauthorized access to user accounts or further compromise of institutional networks if credentials are reused or if malware is deployed. While the vulnerability does not directly allow system compromise, the indirect impact on user trust and potential credential theft could disrupt educational services and damage institutional reputations. Additionally, given the sensitivity of educational data and compliance requirements under GDPR, any resulting data breaches could have regulatory consequences. The impact is heightened in environments where users are less aware of phishing risks or where multi-factor authentication is not enforced.

1. Upgrade all Opencast instances to version 12.5 or later to apply the official fix that eliminates the open redirect vulnerability. 2. Implement strict URL validation and sanitization on any custom or legacy authentication or redirection mechanisms to ensure redirects are only to trusted internal URLs. 3. Educate users, especially authenticated users, about the risks of clicking on suspicious links, even if they appear to originate from trusted platforms. 4. Deploy multi-factor authentication (MFA) to reduce the risk of credential compromise from phishing attacks leveraging this vulnerability. 5. Monitor web server and application logs for unusual redirect patterns or access to the Paella authentication page with suspicious parameters. 6. Use web application firewalls (WAFs) with rules to detect and block open redirect attempts targeting the vulnerable endpoints. 7. Conduct phishing simulations and awareness campaigns tailored to the academic environment to improve user vigilance. 8. Review and restrict the use of URL parameters in authentication flows to minimize attack surface.