CVE-2026-20882: WebSocket API DOS Vulnerability

CVE-2026-20882 Overview

CVE-2026-20882 is a missing rate limiting vulnerability in a WebSocket Application Programming Interface (API) that fails to restrict the number of authentication requests. This security weakness (CWE-307: Improper Restriction of Excessive Authentication Attempts) enables attackers to conduct denial-of-service (DoS) attacks by overwhelming the authentication mechanism, potentially suppressing or mis-routing legitimate charger telemetry data. Additionally, the vulnerability facilitates brute-force attacks that could grant unauthorized access to the affected system.

Critical Impact

This network-accessible vulnerability allows unauthenticated remote attackers to disrupt critical electric vehicle charging infrastructure operations or potentially gain unauthorized system access through sustained brute-force attacks.

Affected Products

• WebSocket API for EV charger management systems
• Mobiliti EV charging infrastructure components
• ICS/OT systems utilizing the vulnerable WebSocket authentication endpoint

Discovery Timeline

• 2026-03-06 - CVE CVE-2026-20882 published to NVD
• 2026-03-10 - Last updated in NVD database

Technical Details for CVE-2026-20882

Vulnerability Analysis

The vulnerability exists due to the WebSocket API's failure to implement proper rate limiting controls on authentication requests. In a properly secured implementation, the API would track and limit the frequency of authentication attempts from individual sources, typically implementing exponential backoff or account lockout mechanisms after repeated failures.

Without these protections, the authentication endpoint becomes susceptible to two primary attack scenarios. First, an attacker can flood the WebSocket connection with authentication requests at high volume, consuming server resources and potentially causing service degradation or complete denial of service. This is particularly concerning in industrial control system (ICS) environments where the affected charger telemetry could be suppressed or mis-routed, leading to operational visibility loss.

Second, the lack of rate limiting removes a critical barrier to credential brute-force attacks. Attackers can systematically attempt credential combinations at machine speed without triggering defensive lockouts, significantly increasing the probability of successful unauthorized access.

Root Cause

The root cause is the absence of authentication rate limiting controls in the WebSocket API implementation. The system does not track the number or frequency of authentication attempts, nor does it implement protective mechanisms such as request throttling, account lockout policies, CAPTCHA challenges, or IP-based blocking after suspicious activity patterns.

Attack Vector

This vulnerability is exploitable over the network without authentication. An attacker can establish a WebSocket connection to the vulnerable API endpoint and initiate unlimited authentication requests. The attack requires no privileges, no user interaction, and has low complexity to execute.

For denial-of-service exploitation, the attacker generates a high volume of authentication requests designed to exhaust server resources or saturate connection handling capacity. For brute-force attacks, the attacker systematically attempts credential combinations, potentially using credential stuffing techniques with leaked password databases or dictionary-based attacks.

The vulnerability is documented in CISA ICS Advisory ICSA-26-062-06, which provides additional context for organizations operating affected ICS/OT infrastructure.

Detection Methods for CVE-2026-20882

Indicators of Compromise

• Abnormally high volume of WebSocket connection attempts from single IP addresses or IP ranges
• Rapid succession of failed authentication attempts against the WebSocket API
• Unusual patterns in authentication request timing suggesting automated tooling
• Degraded charger telemetry connectivity or data gaps coinciding with network anomalies

Detection Strategies

• Implement network monitoring to baseline normal WebSocket authentication patterns and alert on statistical deviations
• Deploy intrusion detection rules to identify rapid authentication attempt sequences exceeding normal operational thresholds
• Monitor for connection flooding patterns targeting WebSocket endpoints
• Correlate authentication failures with source IP reputation data to identify known attack infrastructure

Monitoring Recommendations

• Enable verbose logging on WebSocket API authentication events including source IP, timestamp, and request metadata
• Configure SIEM rules to aggregate and alert on authentication failure rates per source
• Establish baseline metrics for normal authentication traffic to enable anomaly detection
• Monitor charger telemetry availability as an indirect indicator of potential DoS impact

How to Mitigate CVE-2026-20882

Immediate Actions Required

• Contact Mobiliti through their Customer Support Page for vendor-specific guidance and patches
• Review the CISA ICS Advisory ICSA-26-062-06 for detailed mitigation instructions
• Implement network-level rate limiting using a web application firewall (WAF) or reverse proxy in front of the WebSocket API
• Restrict network access to the vulnerable API endpoint to trusted IP ranges where operationally feasible

Patch Information

Organizations should consult the vendor advisory and CISA ICS Advisory ICSA-26-062-06 for official patch availability. The GitHub CSAF JSON File contains structured vulnerability data including remediation guidance.

Workarounds

• Deploy a reverse proxy or API gateway with rate limiting capabilities to throttle authentication requests before they reach the vulnerable endpoint
• Implement IP-based access controls to restrict WebSocket API access to authorized network segments
• Configure network-level connection rate limits to mitigate DoS attack impact
• Enable additional authentication factors where supported to reduce brute-force attack effectiveness

# Example nginx rate limiting configuration for WebSocket endpoints
# Add to nginx.conf or site configuration

# Define rate limiting zone (10 requests per second per IP)
limit_req_zone $binary_remote_addr zone=ws_auth_limit:10m rate=10r/s;

# Apply to WebSocket authentication location
location /ws/auth {
    limit_req zone=ws_auth_limit burst=20 nodelay;
    limit_req_status 429;
    
    proxy_pass http://backend_websocket;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
}