CVE-2026-72598 in Fusio
Summary
by MITRE • 08/11/2026
A server-side request forgery vulnerability in Apioo Fusio 8.8.3 allows authenticated consumer-role users to make the server issue HTTP requests to internal network addresses by registering a webhook URL pointing to an internal host. The webhook registration endpoint validates URL syntax via FILTER_VALIDATE_URL but applies no IP or host denylist. When the registered event fires, the server issues an HTTP POST to the attacker-supplied internal URL.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability in Apioo Fusio 8.8.3 represents a critical server-side request forgery flaw that enables authenticated users with consumer roles to bypass network security controls and access internal systems. The issue stems from insufficient input validation mechanisms within the webhook registration functionality, creating an attack vector where malicious actors can manipulate the system to make unauthorized HTTP requests to internal network addresses.
The technical implementation of this vulnerability exploits a fundamental security oversight in the URL validation process. While the system employs FILTER_VALIDATE_URL for syntax verification, it fails to implement any form of IP address or hostname denylisting that would prevent access to internal network resources. This validation gap allows attackers to register webhook URLs pointing to internal hosts such as 192.168.x.x ranges, localhost addresses, or other private network endpoints that should remain inaccessible from external interfaces.
The operational impact of this vulnerability is substantial as it transforms a limited user role into a potential reconnaissance and exploitation tool for internal network mapping. When an event triggers the registered webhook, the server automatically executes HTTP POST requests to the attacker-controlled internal URL without proper authorization checks or network boundary enforcement. This behavior creates opportunities for attackers to perform internal service enumeration, gather sensitive information from internal APIs, or even attempt further attacks against vulnerable internal services.
Security professionals should recognize this vulnerability as a direct violation of secure coding practices that align with CWE-918, which addresses server-side request forgery vulnerabilities. The flaw also demonstrates characteristics consistent with ATT&CK technique T1071.004, where adversaries use application layer protocols to establish communication channels for command and control operations. Organizations should implement immediate mitigations including the deployment of comprehensive URL validation that includes IP address filtering, hostname denylisting, and network segmentation controls.
The remediation approach requires implementing strict validation mechanisms that prevent registration of webhook URLs pointing to internal network ranges, loopback addresses, or private IP space. Security controls should enforce network boundary checks at the server level, ensuring that outbound HTTP requests are restricted to legitimate external endpoints only. Additionally, organizations should consider implementing web application firewalls and network access control lists to provide defense-in-depth protection against similar vulnerabilities in other applications.
This vulnerability highlights the importance of comprehensive input validation and the principle of least privilege in application security design. The absence of proper access controls during webhook processing demonstrates how seemingly minor implementation gaps can create significant security risks, particularly when dealing with authenticated user inputs that can influence server behavior. Organizations must prioritize robust validation frameworks that consider not just syntax but also semantic security implications of user-supplied data to prevent such critical vulnerabilities from being exploited in production environments.