CVE-2026-31904 is a vulnerability classified under CWE-307 (Improper Restriction of Excessive Authentication Attempts) found in the CTEK Chargeportal product, which is used for managing electric vehicle charging stations. The core issue lies in the WebSocket API's failure to impose any restrictions on the number of authentication requests that can be made. This absence of rate limiting allows an attacker to flood the authentication mechanism with requests, leading to two primary attack vectors: denial-of-service (DoS) and brute-force attacks. The DoS attack can suppress or mis-route legitimate charger telemetry data, disrupting the monitoring and management of charging stations, which could impact operational continuity. The brute-force attack vector enables an attacker to attempt numerous authentication attempts without restriction, increasing the likelihood of unauthorized access to the system. The vulnerability is remotely exploitable over the network without requiring any prior authentication or user interaction, making it easier for attackers to exploit. All versions of the Chargeportal product are affected, and no patches or mitigations have been officially released at the time of publication. The CVSS v3.1 base score is 7.5, indicating a high severity primarily due to the impact on availability and the ease of exploitation. Although no known exploits have been reported in the wild yet, the vulnerability represents a significant risk to organizations relying on CTEK Chargeportal for their EV charging infrastructure management.

The impact of CVE-2026-31904 is primarily on the availability and potentially the integrity of the CTEK Chargeportal system. By enabling denial-of-service attacks, attackers can disrupt the telemetry data flow from EV chargers, which may lead to operational outages, inaccurate monitoring, and potential safety risks if charging stations are not properly managed. The brute-force attack vector threatens unauthorized access, which could lead to further compromise of the system, manipulation of charging operations, or exposure of sensitive operational data. For organizations managing large EV charging networks, this could result in significant service disruptions, financial losses, and reputational damage. The lack of authentication or user interaction requirements lowers the barrier for attackers, increasing the likelihood of exploitation. Given the increasing adoption of EV infrastructure globally, the threat could affect critical transportation and energy sectors, especially in regions with high EV penetration and reliance on CTEK products.

To mitigate CVE-2026-31904, organizations should implement strict rate limiting on authentication requests at the WebSocket API level to prevent abuse through excessive authentication attempts. Deploying Web Application Firewalls (WAFs) or API gateways capable of detecting and throttling abnormal authentication request patterns is recommended. Monitoring and alerting on unusual authentication traffic can help detect ongoing brute-force or DoS attempts early. Network segmentation and limiting exposure of the Chargeportal management interfaces to trusted networks or VPNs can reduce attack surface. Employing multi-factor authentication (MFA) where possible can add an additional layer of defense against unauthorized access. Organizations should engage with CTEK for official patches or updates and apply them promptly once available. Additionally, conducting regular security assessments and penetration testing focused on authentication mechanisms can help identify and remediate similar weaknesses proactively.