CVE-2025-66132 is a medium-severity authorization bypass vulnerability identified in FAPI Business s.r.o.'s FAPI Member software, a membership and client management platform widely used by small and medium enterprises. The vulnerability stems from incorrectly configured access control security levels that allow an attacker to manipulate a user-controlled key parameter to bypass authorization mechanisms. This means that an unauthenticated attacker can potentially gain unauthorized access to restricted resources or perform actions beyond their privileges without needing any user interaction. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N) indicates that the attack can be executed remotely over the network with low attack complexity, no privileges or user interaction required, and impacts confidentiality and integrity but not availability. Although no known exploits are currently reported in the wild, the vulnerability poses a significant risk because it undermines the fundamental access control model of the application. The affected versions include all releases up to and including 2.2.26. The root cause is the failure to properly validate or restrict the user-controlled key used in access control decisions, leading to an authorization bypass. This vulnerability could allow attackers to view or modify sensitive membership data, client information, or other protected resources managed by FAPI Member. Since FAPI Member is used primarily in European markets for membership management, the exposure is geographically relevant. The lack of available patches at the time of disclosure necessitates immediate configuration reviews and compensating controls to mitigate risk.

For European organizations, this vulnerability could lead to unauthorized disclosure and modification of sensitive membership or client data, potentially violating data protection regulations such as GDPR. The confidentiality and integrity of business-critical information managed by FAPI Member could be compromised, leading to reputational damage, financial loss, and regulatory penalties. Since the vulnerability requires no authentication or user interaction, it increases the risk of automated exploitation attempts from external attackers. Organizations relying on FAPI Member for managing memberships, subscriptions, or client relationships may face disruptions in trust and service integrity. The medium severity rating reflects the moderate but tangible risk to data confidentiality and integrity without direct impact on system availability. However, the ease of exploitation and the critical nature of the data involved make this a significant concern for European SMEs and enterprises using this software.

Organizations should immediately audit their FAPI Member access control configurations to ensure that user-controlled keys are properly validated and cannot be manipulated to bypass authorization. Implement strict input validation and sanitization on all parameters influencing access control decisions. Monitor application logs for unusual access patterns or attempts to use unexpected key values. Restrict network access to the FAPI Member application to trusted IP ranges where feasible. Engage with FAPI Business s.r.o. to obtain and apply security patches or updates addressing this vulnerability as soon as they become available. Consider deploying web application firewalls (WAFs) with custom rules to detect and block attempts to exploit this authorization bypass. Additionally, review and reinforce internal policies around membership data access and perform regular security assessments to detect potential weaknesses. Finally, ensure incident response plans are updated to handle potential exploitation scenarios involving unauthorized data access.