CVE-2026-20792: Chargemap.com WebSocket DOS Vulnerability

CVE-2026-20792 Overview

CVE-2026-20792 is a high-severity vulnerability affecting the Chargemap WebSocket Application Programming Interface (API). The vulnerability stems from the absence of rate limiting controls on authentication requests, which can be exploited by attackers to conduct denial-of-service (DoS) attacks or brute-force authentication attempts.

The WebSocket API lacks restrictions on the number of authentication requests that can be submitted. This absence of rate limiting may allow an attacker to conduct denial-of-service attacks by suppressing or misrouting legitimate charger telemetry, or conduct brute-force attacks to gain unauthorized access to the charging infrastructure platform.

Critical Impact

Attackers can exploit this vulnerability to disrupt electric vehicle charging infrastructure operations or gain unauthorized access through brute-force attacks against the WebSocket authentication mechanism.

Affected Products

• Chargemap chargemap.com (all versions)

Discovery Timeline

• 2026-02-27 - CVE-2026-20792 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-20792

Vulnerability Analysis

This vulnerability is classified under CWE-307 (Improper Restriction of Excessive Authentication Attempts). The Chargemap WebSocket API does not implement adequate rate limiting mechanisms on its authentication endpoints. This architectural weakness allows malicious actors to submit an unlimited number of authentication requests without being blocked or throttled.

The vulnerability poses significant risks to critical infrastructure, as Chargemap is used for electric vehicle charging station management. Successful exploitation could disrupt charging operations, manipulate telemetry data, or provide unauthorized access to the charging network management system.

Root Cause

The root cause is the absence of rate limiting controls on the WebSocket API authentication mechanism. Properly implemented rate limiting would restrict the number of authentication attempts allowed within a specific time window, preventing both brute-force attacks and resource exhaustion scenarios.

Without these controls, the API accepts and processes every authentication request regardless of volume or source, creating opportunities for credential stuffing, password spraying, and denial-of-service attacks targeting the authentication subsystem.

Attack Vector

The vulnerability is exploitable remotely over the network without requiring authentication or user interaction. An attacker can target the WebSocket API endpoint directly with automated tools to either:

1. Denial of Service: Flood the authentication endpoint with requests to exhaust server resources, disrupting legitimate charger telemetry and user access
2. Brute-Force Attack: Systematically attempt credential combinations to gain unauthorized access to charging station management functions

The attack does not require prior authentication, making it accessible to any network-connected attacker who can reach the WebSocket API endpoint.

Detection Methods for CVE-2026-20792

Indicators of Compromise

• Unusually high volume of WebSocket authentication requests from single or multiple IP addresses
• Failed authentication attempts occurring at rates exceeding normal user behavior patterns
• Charger telemetry data gaps or delays indicating potential service disruption
• Unexpected authentication successes following periods of high-volume login attempts

Detection Strategies

• Implement logging and alerting for authentication request rates that exceed baseline thresholds
• Monitor WebSocket connection patterns for anomalous behavior such as rapid connection/disconnection cycles
• Deploy network intrusion detection rules to identify brute-force authentication patterns
• Analyze authentication logs for distributed attacks originating from multiple source IPs

Monitoring Recommendations

• Establish baseline metrics for normal WebSocket API authentication traffic
• Configure real-time alerts for authentication rate anomalies and failed login spikes
• Monitor charging station telemetry connectivity for unexpected dropouts or delays
• Review authentication logs regularly for signs of credential stuffing or password spraying campaigns

How to Mitigate CVE-2026-20792

Immediate Actions Required

• Implement rate limiting on the WebSocket API authentication endpoint immediately
• Deploy Web Application Firewall (WAF) rules to throttle excessive authentication requests
• Consider IP-based blocking for sources generating anomalous authentication traffic
• Enable enhanced logging and monitoring for all authentication events
• Review and strengthen password policies to reduce brute-force attack success probability

Patch Information

Contact Chargemap through their Support Page for the latest security updates and patching guidance. Additional technical details are available in the CISA ICS Advisory ICSA-26-057-05 and the corresponding GitHub CSAF Document.

Workarounds

• Deploy a reverse proxy or API gateway with rate limiting capabilities in front of the WebSocket API
• Implement account lockout policies after a defined number of failed authentication attempts
• Use network segmentation to restrict access to the WebSocket API from untrusted networks
• Consider implementing CAPTCHA or proof-of-work challenges after initial failed authentication attempts
• Enable multi-factor authentication to reduce the impact of potential credential compromise

# Example rate limiting configuration for nginx reverse proxy
limit_req_zone $binary_remote_addr zone=ws_auth:10m rate=5r/s;

location /websocket/auth {
    limit_req zone=ws_auth burst=10 nodelay;
    limit_req_status 429;
    proxy_pass http://chargemap_backend;
}