CVE-2025-55886 is an IDOR vulnerability identified in the ARD platform's payment history API endpoint, specifically involving the 'fe_uid' parameter. This parameter is intended to specify the user whose payment history is being requested. Due to insufficient authorization checks, an authenticated attacker can manipulate this parameter to retrieve payment histories of other users, bypassing access controls. The vulnerability does not require user interaction but does require the attacker to be authenticated, which implies some level of access to the system. The CVSS 3.1 score of 6.5 reflects a medium severity, driven by the high confidentiality impact (unauthorized disclosure of sensitive payment data), low attack complexity, and the network attack vector. There is no impact on integrity or availability. No patches or exploits are currently reported, but the vulnerability poses a significant risk of sensitive data leakage. The underlying issue aligns with CWE-693, indicating improper authorization logic. This vulnerability highlights the need for robust access control enforcement on API parameters that reference user-specific data. Organizations using ARD should review their API implementations to ensure that user identifiers cannot be manipulated to access unauthorized data.

For European organizations, the primary impact is the unauthorized disclosure of sensitive payment history data, which can lead to privacy violations, regulatory non-compliance (e.g., GDPR), reputational damage, and potential financial fraud. Since the vulnerability requires authentication, insider threats or compromised accounts could be leveraged to exploit this flaw. The exposure of payment histories could also facilitate targeted phishing or social engineering attacks. Although the vulnerability does not affect system integrity or availability, the confidentiality breach alone is significant, especially given Europe's strict data protection laws. Organizations handling large volumes of payment data or operating in regulated sectors such as finance, healthcare, or e-commerce are particularly at risk. The lack of known exploits reduces immediate risk but does not eliminate the potential for future attacks once the vulnerability becomes widely known.

To mitigate CVE-2025-55886, organizations should implement strict authorization checks on the 'fe_uid' parameter within the payment history API to ensure that users can only access their own data. This includes validating that the authenticated user's identity matches the requested user ID or enforcing role-based access controls. Conduct a comprehensive audit of all API endpoints handling user-specific data to identify and remediate similar IDOR vulnerabilities. Employ logging and monitoring to detect unusual access patterns indicative of exploitation attempts. Additionally, implement multi-factor authentication to reduce the risk of account compromise. If possible, apply rate limiting on API calls to hinder automated exploitation. Since no patches are currently available, consider temporary compensating controls such as restricting API access or isolating sensitive endpoints until a fix is released. Finally, educate developers on secure coding practices related to access control and parameter validation.