CVE-2025-64471 is a vulnerability affecting multiple versions of Fortinet FortiWeb, a widely deployed web application firewall product. The flaw arises from the improper use of password hashes in the authentication process, where the system accepts the hash itself as a valid credential rather than requiring the original password. This weakness allows an unauthenticated attacker to craft HTTP or HTTPS requests containing a password hash and successfully authenticate to the FortiWeb device. The vulnerability spans FortiWeb versions 7.0.0 through 8.0.1, covering several major releases. Exploitation does not require user interaction but does require network access to the management interface. The CVSS 3.1 base score is 4.4 (medium), reflecting that while the attack vector is network-based with low complexity, it requires privileges (PR:H) indicating some level of precondition or knowledge, and impacts integrity without affecting confidentiality or availability. Successful exploitation could allow attackers to escalate privileges, potentially modifying firewall policies or configurations, which could undermine the security posture of protected web applications. No public exploits or active exploitation have been reported to date. The vulnerability is categorized under CWE-836, indicating the use of password hashes instead of passwords for authentication, a design flaw that weakens authentication mechanisms. Fortinet has published the vulnerability but no patch links are currently provided, suggesting that remediation may be pending or forthcoming.

For European organizations, this vulnerability poses a significant risk to the integrity of their web application firewall defenses. FortiWeb devices are often deployed to protect critical web applications and sensitive data. Unauthorized access through this flaw could allow attackers to alter firewall rules, disable protections, or gain further footholds within the network. This could lead to increased exposure to web-based attacks such as SQL injection, cross-site scripting, or data exfiltration. The impact is particularly critical for sectors such as finance, healthcare, government, and telecommunications, where Fortinet products have strong market presence and where web application security is paramount. Additionally, the ability to authenticate without proper credentials could facilitate lateral movement or persistence within networks, complicating incident response efforts. Although the CVSS score is medium, the potential for privilege escalation and subsequent compromise of critical infrastructure elevates the threat level for organizations relying on FortiWeb. The absence of known exploits in the wild provides a window for proactive mitigation, but the risk remains substantial given the widespread use of FortiWeb in Europe.

European organizations should immediately restrict access to FortiWeb management interfaces to trusted networks and IP addresses, ideally isolating them from general internet exposure. Implement network segmentation and firewall rules to limit who can reach FortiWeb devices. Enable detailed logging and monitoring of authentication attempts to detect anomalous or repeated failed logins that may indicate exploitation attempts. Organizations should engage with Fortinet support to obtain patches or updates as soon as they become available and prioritize their deployment. Until patches are applied, consider deploying additional web application firewall layers or compensating controls to reduce risk. Conduct thorough audits of FortiWeb configurations and review access control policies to minimize the attack surface. Security teams should prepare incident response plans specific to FortiWeb compromise scenarios. Finally, educate administrators on the risks of using password hashes in authentication and encourage the use of multi-factor authentication where supported to add an additional layer of defense.