CVE-2025-8616 is a medium severity authentication bypass vulnerability affecting OpenText Advanced Authentication version 6.5.0 and earlier. The vulnerability is categorized under CWE-294, which relates to improper authentication mechanisms. Specifically, the flaw allows a malicious browser plugin to capture and replay the user authentication process, effectively bypassing the intended authentication controls. This capture-replay attack exploits the lack of sufficient anti-replay protections in the authentication protocol or implementation. When a user authenticates, the plugin records the authentication tokens or messages exchanged and later replays them to gain unauthorized access without needing valid credentials. The vulnerability does not require prior authentication but does require user interaction, such as the user visiting a malicious or compromised website that hosts the malicious browser plugin. The CVSS 4.0 vector indicates the attack is network-based (AV:N), requires high attack complexity (AC:H), no privileges (PR:N), user interaction (UI:P), and impacts confidentiality highly (VC:H), with low impact on integrity and availability (VI:L, VA:L). The vulnerability scope is unchanged (SC:N), and no security requirements are altered (SI:N, SA:N). No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability affects organizations using OpenText Advanced Authentication for securing access to their systems, potentially allowing attackers to bypass authentication and gain unauthorized access to sensitive resources.

For European organizations, this vulnerability poses a significant risk to the confidentiality of sensitive information and access control integrity. Organizations relying on OpenText Advanced Authentication for identity and access management could see unauthorized access to internal systems, potentially leading to data breaches, intellectual property theft, or lateral movement within networks. Sectors such as finance, government, healthcare, and critical infrastructure that often use advanced authentication solutions are particularly at risk. The attack requires user interaction and a malicious browser plugin, which means social engineering or supply chain attacks targeting browser extensions could be leveraged. Given the high confidentiality impact, attackers could exfiltrate sensitive personal data protected under GDPR, leading to regulatory penalties and reputational damage. The medium severity rating reflects the complexity of exploitation and the need for user interaction, but the potential consequences for compromised accounts are serious. The lack of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits over time.

European organizations should implement the following specific mitigations: 1) Immediately audit and monitor the use of OpenText Advanced Authentication version 6.5.0 or earlier and plan for an upgrade to a patched or newer version once available. 2) Restrict or monitor browser extensions/plugins installation policies, especially in managed environments, to prevent installation of malicious plugins capable of capturing authentication data. 3) Employ additional multi-factor authentication (MFA) layers that are resistant to replay attacks, such as hardware tokens with challenge-response or biometric factors. 4) Implement network-level anomaly detection to identify unusual authentication patterns or repeated authentication attempts from the same client. 5) Educate users about the risks of installing untrusted browser extensions and phishing attempts that could lead to plugin installation. 6) Use secure authentication protocols that incorporate anti-replay mechanisms, such as nonce or timestamp validation, to prevent replay attacks. 7) Monitor logs for suspicious authentication activity and conduct regular security assessments focusing on authentication flows. 8) Coordinate with OpenText support for timely updates and patches addressing this vulnerability.