CVE-2026-22912: Authentication Bypass Vulnerability

CVE-2026-22912 Overview

CVE-2026-22912 is an Open Redirect vulnerability (CWE-601) affecting SICK industrial systems. Improper validation of a login parameter allows attackers to redirect users to malicious websites after authentication. This vulnerability can be exploited to conduct phishing attacks, steal credentials from unsuspecting users, or distribute malware by leveraging the trust users place in legitimate login pages.

Critical Impact

Attackers can manipulate the redirect parameter during authentication to send users to attacker-controlled websites, enabling credential theft and phishing attacks against industrial system operators.

Affected Products

• SICK Industrial Control Systems (specific product versions not disclosed in advisory)
• Systems utilizing SICK authentication components with redirect functionality

Discovery Timeline

• 2026-01-15 - CVE-2026-22912 published to NVD
• 2026-01-16 - Last updated in NVD database

Technical Details for CVE-2026-22912

Vulnerability Analysis

This vulnerability stems from improper validation of URL redirect parameters in the authentication workflow. When a user authenticates to a SICK industrial system, the application accepts a redirect URL parameter that specifies where the user should be directed after successful login. However, insufficient validation of this parameter allows attackers to craft malicious login links that redirect authenticated users to attacker-controlled external websites.

The attack requires user interaction—specifically, a user must click on a malicious link and complete the authentication process. Once authenticated, the victim is automatically redirected to the attacker's domain while believing they are still interacting with the legitimate SICK system.

Root Cause

The root cause is CWE-601: URL Redirection to Untrusted Site (Open Redirect). The application fails to properly validate or sanitize the redirect URL parameter before using it in the post-authentication redirect. This allows external URLs to be accepted when only internal or whitelisted URLs should be permitted.

Attack Vector

The attack is network-based and requires the attacker to craft a malicious URL containing the legitimate SICK system's login endpoint with a manipulated redirect parameter pointing to an attacker-controlled domain. The attacker then distributes this link through phishing emails, compromised websites, or other social engineering techniques.

When a user clicks the link and authenticates, the trust established through the legitimate login process carries over as the user is seamlessly redirected to the malicious site. The attacker's site can then present a fake session timeout page to harvest credentials, deliver malware, or perform other malicious actions.

The vulnerability can be exploited by constructing a URL where the redirect parameter points to an external domain. For example, legitimate login flows use internal paths like /dashboard for the redirect target, but attackers can substitute external URLs that the server fails to validate before issuing the redirect response. For complete technical details, refer to the SICK CSAF PDF Advisory.

Detection Methods for CVE-2026-22912

Indicators of Compromise

• Authentication logs showing successful logins followed by redirects to external domains
• Network traffic showing HTTP 302/301 responses from authentication endpoints redirecting to non-internal URLs
• User reports of unexpected website redirections after login attempts
• Phishing emails containing URLs to legitimate SICK login pages with suspicious query parameters

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block requests with external URLs in redirect parameters
• Monitor authentication endpoint access logs for unusual redirect parameter values
• Deploy network intrusion detection signatures for HTTP responses containing redirects to external domains from internal systems
• Review proxy logs for connections to suspicious domains immediately following authentication events

Monitoring Recommendations

• Enable detailed logging for all authentication-related endpoints and redirect actions
• Configure alerts for redirect responses containing external domain references
• Implement URL parameter monitoring on authentication endpoints to detect manipulation attempts
• Establish baseline redirect behavior and alert on anomalies

How to Mitigate CVE-2026-22912

Immediate Actions Required

• Review authentication workflows for any exposed redirect parameters
• Implement strict URL validation on all redirect parameters, allowing only whitelisted internal paths
• Educate users about the risks of clicking login links from untrusted sources
• Consider implementing relative URL redirects only, rejecting any absolute URLs

Patch Information

SICK has published security advisories addressing this vulnerability. System administrators should consult the SICK PSIRT Resource page for the latest patch information and updates. Additionally, the SICK CSAF JSON Advisory and SICK CSAF PDF Advisory provide detailed remediation guidance.

Organizations operating industrial control systems should also review the CISA ICS Best Practices for additional security hardening recommendations.

Workarounds

• Implement a whitelist of allowed redirect destinations and validate all redirect parameters against this list
• Use indirect redirect mapping where the parameter references an index or key rather than the actual URL
• Deploy a web application firewall with rules to block requests containing external URLs in redirect parameters
• Consider disabling redirect functionality temporarily until patches can be applied

# Example: Web server configuration to restrict redirects (Apache)
# Add to authentication location block to limit redirect targets
<Location /login>
    # Only allow redirects to internal paths
    Header edit Location "^https?://(?!internal\.domain\.com)" "/"
    
    # Log all redirect attempts for monitoring
    CustomLog /var/log/httpd/redirect_audit.log combined
</Location>