CVE-2025-61546 is a critical security vulnerability identified in edu Business Solutions Print Shop Pro WebDesk version 18.34. The flaw exists in the /PSP/appNET/Store/CartV12.aspx/GetUnitPrice endpoint, which is responsible for calculating unit prices during the purchase process. The vulnerability arises because the application relies solely on client-side input validation to enforce quantity constraints, allowing remote attackers to submit negative quantities for items. This manipulation can cause the system to process transactions with negative values, leading to financial discrepancies such as unauthorized credits or refunds. The vulnerability does not require any authentication or user interaction, making it remotely exploitable over the network. The CVSS v3.1 score of 9.1 reflects the high impact on confidentiality and integrity, as attackers can alter financial data and potentially disrupt business operations. Although no known exploits are reported in the wild, the ease of exploitation and the critical nature of the flaw necessitate urgent attention. The root cause aligns with CWE-20, indicating improper input validation. Since the vulnerability affects a financial transaction endpoint, exploitation could result in significant monetary losses and damage to organizational trust. The lack of available patches at the time of disclosure emphasizes the need for immediate compensating controls and monitoring.

For European organizations, this vulnerability poses a severe risk of financial fraud and operational disruption. Organizations using Print Shop Pro WebDesk for managing print service orders could experience unauthorized financial credits or manipulated billing, leading to direct monetary losses. The integrity of financial records and transactional data may be compromised, affecting accounting accuracy and audit compliance. Confidentiality is also impacted as attackers could infer pricing and purchasing patterns by manipulating requests. The lack of authentication requirement broadens the attack surface, allowing external threat actors to exploit the flaw remotely without insider access. This could undermine trust in financial systems and damage reputations, especially for public sector institutions and large enterprises relying on this software. The vulnerability could also facilitate further attacks by enabling attackers to create financial inconsistencies that mask other malicious activities. Given the critical CVSS score and the financial nature of the flaw, the potential impact on European businesses and government agencies is substantial.

Immediate mitigation should focus on implementing robust server-side input validation to enforce quantity constraints, ensuring that negative values are rejected regardless of client input. Organizations should monitor transaction logs for unusual patterns such as negative quantity submissions or unexpected credits. Until an official patch is released, consider deploying web application firewalls (WAFs) with custom rules to block suspicious requests targeting the vulnerable endpoint. Conduct thorough audits of recent transactions to identify and rectify any financial discrepancies caused by exploitation attempts. Engage with edu Business Solutions for timely patch releases and apply updates as soon as they become available. Additionally, restrict access to the vulnerable endpoint through network segmentation or IP whitelisting where feasible. Educate staff about the vulnerability and encourage vigilance for any anomalies in billing or order processing. Finally, integrate anomaly detection tools that can flag irregular purchase behaviors indicative of exploitation.