CVE-2025-34155 is a vulnerability classified under CWE-204 (Observable Response Discrepancy) found in Tibbo Systems AggreGate Network Manager versions earlier than 6.40.05. The flaw exists in the login functionality where the system returns different error messages depending on whether the username supplied exists or not. This discrepancy allows an unauthenticated remote attacker to perform user enumeration by analyzing the system's responses to login attempts. User enumeration is a critical reconnaissance step that can significantly aid attackers in crafting targeted brute-force or credential-stuffing attacks against valid accounts. The vulnerability requires no authentication or user interaction and can be exploited remotely over the network. Although no public exploits have been reported, the vulnerability's presence increases the attack surface by enabling attackers to identify valid usernames, which is often the first step in compromising accounts. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges or user interaction required (PR:N/UI:N), and low impact on confidentiality (VC:L) with no impact on integrity or availability. This suggests the vulnerability primarily aids in information gathering rather than direct system compromise. Tibbo AggreGate Network Manager is widely used in industrial automation, IoT device management, and network monitoring, making this vulnerability relevant for organizations relying on these systems for operational technology (OT) and IT convergence.

For European organizations, this vulnerability poses a moderate risk primarily by enabling attackers to enumerate valid user accounts remotely without authentication. This can lead to increased success rates of brute-force or credential-stuffing attacks, potentially resulting in unauthorized access to critical network management systems. Given AggreGate Network Manager’s role in managing industrial automation and IoT devices, a compromised account could allow attackers to manipulate or disrupt operational technology environments, leading to operational downtime, safety hazards, or data breaches. The impact is particularly significant for sectors such as manufacturing, energy, transportation, and utilities, which are prevalent across Europe and often rely on Tibbo’s solutions. Additionally, the ability to identify valid usernames can facilitate further targeted attacks, including phishing or social engineering campaigns. While the vulnerability itself does not directly compromise system integrity or availability, it lowers the barrier for subsequent, more damaging attacks. Organizations with regulatory obligations under GDPR and NIS Directive must consider the potential for data exposure and operational disruption stemming from exploitation of this vulnerability.

To mitigate CVE-2025-34155, European organizations should immediately upgrade Tibbo AggreGate Network Manager to version 6.40.05 or later, where the vulnerability has been addressed. In the absence of an available patch, organizations should implement the following specific measures: 1) Standardize and unify authentication failure messages to prevent username enumeration by ensuring error responses are identical regardless of username validity. 2) Implement account lockout or throttling mechanisms after a defined number of failed login attempts to hinder brute-force attacks. 3) Deploy web application firewalls (WAFs) or intrusion prevention systems (IPS) with rules designed to detect and block repeated login attempts and anomalous authentication patterns. 4) Enforce multi-factor authentication (MFA) for all administrative and user accounts to reduce the risk of credential compromise. 5) Monitor authentication logs closely for unusual login failures or patterns indicative of enumeration or brute-force activity. 6) Conduct regular security awareness training to alert users about phishing and credential-stuffing risks. 7) Segment and isolate network management systems to limit exposure to untrusted networks. These targeted mitigations go beyond generic advice by focusing on the specific attack vector and operational context of the vulnerability.