CVE-2018-16153 is a high-severity vulnerability affecting Apereo Opencast versions 4.x through 10.x prior to 10.6. The vulnerability involves the unintended transmission of system digest credentials during authentication attempts to arbitrary external services under certain conditions. Specifically, the system sends sensitive authentication data—digest credentials—outside the trusted environment, potentially exposing these credentials to malicious actors controlling or intercepting the external services. The vulnerability is classified under CWE-522, which relates to insufficiently protected credentials. The CVSS 3.1 base score is 7.5, reflecting a network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), high confidentiality impact (C:H), and no impact on integrity or availability (I:N/A:N). This means an unauthenticated attacker can remotely exploit this flaw without user interaction, leading to a complete compromise of confidentiality of the credentials involved. The vulnerability does not affect system integrity or availability directly but poses a significant risk of credential leakage, which can be leveraged for further attacks such as unauthorized access or lateral movement within affected environments. No known exploits in the wild have been reported, and no official patches are linked in the provided data, indicating that organizations must verify their Opencast versions and apply any available updates or mitigations from the vendor promptly.

For European organizations using Apereo Opencast—an open-source video management and lecture capture platform widely adopted by educational institutions and media organizations—this vulnerability poses a significant confidentiality risk. The leakage of system digest credentials to arbitrary external services could allow attackers to impersonate legitimate system components or users, potentially gaining unauthorized access to sensitive video content, user data, or internal systems integrated with Opencast. This could lead to data breaches, violation of privacy regulations such as GDPR, reputational damage, and disruption of educational or media services. Since Opencast is often deployed in academic and research institutions across Europe, the impact extends to the protection of intellectual property and sensitive research data. The absence of required privileges or user interaction for exploitation increases the risk of automated or widespread attacks. Additionally, the exposure of credentials could facilitate further attacks within the network, including privilege escalation or lateral movement, amplifying the overall security risk to European organizations relying on this platform.

European organizations should immediately verify their deployment versions of Apereo Opencast and prioritize upgrading to version 10.6 or later, where this vulnerability is addressed. In the absence of an official patch, organizations should consider the following specific mitigations: 1) Restrict network egress from Opencast servers to only trusted external services to prevent unauthorized transmission of credentials. 2) Implement strict monitoring and logging of outbound authentication attempts to detect anomalous or unexpected external connections. 3) Use network-level controls such as firewalls or proxy servers to block or scrutinize traffic destined for unknown external endpoints. 4) Rotate any system digest credentials that may have been exposed to limit the window of exploitation. 5) Conduct thorough security audits and penetration testing focused on authentication flows within Opencast deployments. 6) Engage with the Opencast community or vendor for any interim patches or recommended configuration changes. 7) Educate system administrators about the risks of credential leakage and enforce the principle of least privilege for system accounts involved in authentication processes.