CVE-2021-45036 is an authentication bypass vulnerability identified in Velneo vClient version 28.1.3. Velneo vClient is a client application used to connect to Velneo application servers, which are typically employed for rapid application development and deployment in business environments. The vulnerability stems from improper authentication controls (classified under CWE-290: Authentication Bypass by Spoofing). Specifically, an attacker who already possesses a victim's username and hashed password can exploit this flaw to spoof the victim's identity to the Velneo server. This means the attacker can impersonate the legitimate user without needing to know the plaintext password or perform additional authentication steps. The vulnerability does not require user interaction beyond the attacker having the hashed credentials, which could be obtained through other means such as credential leaks or interception. No public exploits have been reported in the wild, and no patches are currently linked, indicating that remediation may require vendor intervention or configuration changes. The vulnerability affects only version 28.1.3 of Velneo vClient, suggesting that other versions may not be vulnerable or have been patched. The authentication bypass could allow unauthorized access to sensitive business applications and data managed through Velneo, potentially leading to data exposure, unauthorized transactions, or manipulation of business logic within affected systems.

For European organizations using Velneo vClient 28.1.3, this vulnerability poses a significant risk to the confidentiality and integrity of business-critical applications. Since Velneo is often used in enterprise environments for application development and deployment, an attacker exploiting this flaw could gain unauthorized access to internal systems, potentially leading to data breaches, unauthorized data modification, or disruption of business processes. The ability to spoof authenticated users without needing plaintext passwords increases the risk of lateral movement within networks and escalated privileges. This could impact sectors relying on Velneo solutions, such as manufacturing, logistics, or service providers, where sensitive operational data is processed. Additionally, compromised credentials could be used to bypass audit trails and accountability mechanisms, complicating incident response and forensic investigations. The lack of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially if attackers obtain hashed credentials through other breaches. The medium severity rating reflects the need for vigilance but also the requirement of prior credential compromise, limiting the ease of exploitation. However, organizations with weak credential management or those exposed to phishing and credential theft attacks are at higher risk.

To mitigate this vulnerability, European organizations should first verify if they are running Velneo vClient version 28.1.3 and plan to upgrade to a patched or newer version as soon as it becomes available from Velneo. In the absence of an official patch, organizations should implement compensating controls such as enforcing multi-factor authentication (MFA) at the application or network level to reduce the risk of credential misuse. Monitoring and restricting access to hashed password stores and ensuring secure credential storage practices are critical to prevent attackers from obtaining the necessary hashed credentials. Network segmentation and strict access controls can limit the ability of attackers to reach Velneo servers. Additionally, organizations should enhance logging and anomaly detection to identify suspicious authentication attempts or unusual user behavior indicative of spoofing. Regular credential rotation and the use of strong, unique passwords can reduce the window of opportunity for attackers. Finally, educating users about phishing and credential theft risks will help prevent initial compromise of credentials required for exploitation.