CVE-2026-86405 in Virtual POS Extension
Summary
by MITRE • 10/09/2026
Improper verification of cryptographic signature vulnerability in Sipay Electronic Money and Payment Services Inc. PrestaShop Virtual POS Module allows Signature Spoofing by Improper Validation.
This issue affects PrestaShop Virtual POS Module: from 26.8.1 before 26.9.1.
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Analysis
by VulDB Data Team • 10/09/2026
The vulnerability identified in the Sipay Electronic Money and Payment Services Inc. PrestaShop Virtual POS Module represents a critical failure in cryptographic integrity verification, specifically classified under CWE-347 as Improper Verification of Cryptographic Signature. This flaw exists within module versions ranging from 26.8.1 up to but not including version 26.9.1. The core technical issue stems from the application's inability to properly validate digital signatures associated with payment transaction data or configuration payloads received by the system. In a secure implementation, any cryptographic signature must be verified against a trusted public key before the corresponding plaintext data is processed further within the business logic of the e-commerce platform. However, in this affected version, the validation routine either skips the check entirely, accepts signatures from untrusted sources, or fails to enforce strict format constraints on the signed content. This deficiency allows an attacker to craft malicious payloads that appear legitimate due to valid-looking but improperly validated cryptographic markers, thereby bypassing authentication and authorization controls designed to protect financial transactions.
From a tactical perspective, this vulnerability aligns with MITRE ATT&CK technique T1588.002, which involves obtaining code signing certificates or keys through theft from vulnerable systems, although in this specific context, the exploitation relies more on the application's failure to reject invalid signatures rather than key theft alone. An attacker can exploit this flaw by intercepting communication between the PrestaShop store and the Sipay payment gateway using a man-in-the-middle attack or by directly manipulating API requests if exposed endpoints are accessible without sufficient network-level protections. By spoofing the signature, the adversary can inject arbitrary commands, alter transaction amounts, change recipient accounts, or bypass fraud detection mechanisms embedded within the POS module. The operational impact is severe for merchants utilizing this integration, as it potentially leads to unauthorized fund transfers, financial loss through chargeback manipulation, and compromise of sensitive customer payment data stored in session variables or database records linked to these transactions.
The exploitation scenario typically involves constructing a request where the cryptographic signature field contains valid syntax but corresponds to malicious intent rather than genuine merchant authorization. Because the system does not rigorously verify that the signed content matches the expected schema and origin, it processes the spoofed data as authentic. This can result in privilege escalation within the application context if the POS module has elevated permissions for database writes or API calls. Furthermore, since PrestaShop is a widely used open-source e-commerce platform, this vulnerability affects not just individual merchants but potentially scales across thousands of installations that have not yet applied the necessary patches. The lack of proper signature validation undermines the non-repudiation guarantees provided by digital signatures, making it difficult for businesses to prove the origin and integrity of financial records during audits or legal disputes following a breach.
Mitigation strategies must prioritize immediate remediation through software updates. Merchants operating on affected versions should upgrade the PrestaShop Virtual POS Module to version 26.9.1 or later, where the cryptographic verification logic has been corrected to strictly enforce signature validation against trusted keys and validate payload integrity before processing. In environments where an immediate update is not feasible due to compatibility constraints with other modules or custom code modifications, temporary compensating controls should be implemented at the network perimeter level. This includes deploying Web Application Firewalls configured to detect anomalies in payment API request structures and enforcing strict input validation rules that reject any requests lacking properly formatted cryptographic headers. Additionally, enabling comprehensive logging for all POS transaction attempts allows security teams to monitor for patterns indicative of signature spoofing attacks, such as repeated failures or unusual source IPs attempting to interact with the virtual terminal endpoints. Regular audits of third-party module codebases are also recommended to ensure no other similar vulnerabilities exist within the broader e-commerce stack that could be chained together to achieve deeper system compromise.