Compliance Impact

The vulnerability allows attackers to redirect server requests to internal IP addresses, potentially accessing sensitive internal services or stealing IAM credentials on cloud instances.

Such unauthorized access to internal or sensitive data could lead to violations of data protection regulations like GDPR or HIPAA, which require strict controls over access to personal and sensitive information.

Therefore, if exploited, this SSRF vulnerability could compromise compliance by exposing protected data or internal systems to unauthorized parties.

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Executive Summary

CVE-2026-42194 is a Server-Side Request Forgery (SSRF) vulnerability in Admidio versions prior to 5.0.9. The issue arises because the software validates the resolved IP address of a URL but then uses the original hostname-based URL when making a request with curl_init(). This creates a DNS rebinding Time-of-Check Time-of-Use (TOCTOU) window, allowing an attacker to redirect requests to internal IP addresses by changing the DNS resolution between the validation and the actual request.

This means an attacker can trick the Admidio server into sending requests to internal services, such as the AWS metadata service or localhost, potentially exposing sensitive internal resources.

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Impact Analysis

This vulnerability can allow an attacker to make the Admidio server send HTTPS requests to internal network services that are normally inaccessible from outside. This can lead to unauthorized access to sensitive information such as IAM credentials on cloud instances or other internal services in on-premise environments.

The impact includes potential data exposure and unauthorized internal network access, which can compromise the security of the affected system and its environment.

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Detection Guidance

This vulnerability involves a DNS rebinding TOCTOU window in Admidio's fetch_metadata.php, allowing SSRF attacks by redirecting requests to internal IPs. Detection would involve monitoring for unusual outgoing HTTPS requests from the Admidio server to internal IP addresses such as 169.254.169.254 (AWS metadata service) or localhost (127.0.0.1).

You can check network traffic logs or use network monitoring tools to identify suspicious requests originating from the Admidio server to internal IP ranges.

Additionally, inspecting the Admidio server logs for unexpected calls to fetch_metadata.php or unusual curl requests may help detect exploitation attempts.

Specific commands might include:

• Using tcpdump or similar to capture outgoing traffic to internal IPs: tcpdump -i eth0 host 169.254.169.254 or tcpdump -i eth0 host 127.0.0.1
• Using netstat or ss to check active connections from the Admidio server: netstat -tnp | grep curl or ss -tnp | grep curl
• Reviewing web server or application logs for requests to fetch_metadata.php that might indicate exploitation attempts.

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Mitigation Strategies

The primary mitigation step is to upgrade Admidio to version 5.0.9 or later, where this SSRF vulnerability has been patched.

The patch addresses the issue by properly binding the hostname to the validated IP address using CURLOPT_RESOLVE, preventing DNS rebinding attacks.

Until the upgrade can be applied, consider restricting the Admidio server's outbound network access to prevent connections to internal IP addresses such as 169.254.169.254 and 127.0.0.1.

Monitoring and alerting on suspicious outgoing requests from the Admidio server can also help detect exploitation attempts.

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