CVE-2025-56563 in Zenith Satellite Tracker
Summary
by MITRE • 09/16/2026
A Server-Side Request Forgery vulnerability exists in sat_proxy.php in Zenith Satellite Tracker 1.0. The script accepts an attacker-controlled address URL parameter and passes it to curl_setopt(CURLOPT_URL) without host or scheme validation. An unauthenticated remote attacker can leverage this to make arbitrary HTTP and HTTPS requests from the server to internal networks or cloud metadata services, potentially obtaining sensitive information or pivoting to further attacks.
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Analysis
by VulDB Data Team • 09/16/2026
The vulnerability identified in Zenith Satellite Tracker version 1.0 represents a critical Server-Side Request Forgery flaw located within the sat_proxy.php script component of the application architecture. This specific implementation error stems from an insufficient validation mechanism when processing user-supplied input, specifically targeting the address URL parameter provided by clients during HTTP requests. The core technical failure lies in how the backend PHP code utilizes this untrusted data to configure a cURL session via the CURLOPT_URL option without performing any rigorous checks on the destination host or protocol scheme. By directly passing attacker-controlled values into the network request configuration, the application effectively acts as an open proxy for external actors, allowing them to dictate where and what resources are fetched by the server itself rather than the client browser.
From a technical perspective, this flaw exploits the trust relationship between the web application and its underlying infrastructure or internal services. Because there is no whitelist of allowed domains nor any blacklist filtering for private IP ranges such as 10.x.x.x, 172.16-31.x.x, or 192.168.x.x, an unauthenticated remote attacker can craft malicious requests that force the server to initiate connections to internal network resources. This capability is particularly dangerous in cloud environments where instance metadata services are often accessible via non-routable IP addresses like 169.254.169.254 or through localhost loops. By directing these forged requests toward such endpoints, an attacker can retrieve sensitive configuration data, authentication tokens, and other credentials stored within the server environment without ever needing to authenticate against the application itself.
The operational impact of this vulnerability is severe due to its potential for lateral movement and information disclosure. Once an attacker successfully exfiltrates internal network details or cloud metadata, they gain a significant foothold that can be leveraged for further exploitation. This includes accessing backend databases, interacting with other services on the local network, or stealing session cookies if the server has access to them. The ability to make arbitrary HTTP and HTTPS requests means the attacker is not limited to passive data retrieval; they could potentially trigger actions within internal systems by sending crafted POST requests or exploiting other vulnerabilities in connected services that are exposed only internally but reachable via this proxy mechanism. This transforms a simple information leak into a potential gateway for full system compromise, effectively bypassing perimeter security controls designed to protect the application from external threats.
In terms of industry classification standards, this vulnerability aligns with CWE-918 Server-Side Request Forgery (SSRF), which describes flaws where a web server fetches a remote resource without validating the user-supplied URL. Furthermore, within the MITRE ATT&CK framework, this behavior corresponds to T1557 Adversary-in-the-Middle or more specifically techniques related to Lateral Movement and Credential Access depending on the specific target reached through the forged requests. The lack of input validation also touches upon CWE-20 Improper Input Validation, highlighting a fundamental failure in secure coding practices regarding external control of critical system resources.
To mitigate this vulnerability, immediate remediation steps must focus on implementing strict allow-listing for URL destinations rather than relying on blocklists which are prone to bypasses through encoding tricks or alternative protocols like FTP or Gopher if supported by the cURL library. Developers should parse the provided URL and verify that the hostname resolves only to explicitly trusted public domains, rejecting any request targeting private IP ranges, loopback addresses, or cloud metadata endpoints. Additionally, disabling unnecessary PHP extensions such as libcurl in production environments where they are not strictly required can reduce the attack surface. Implementing network-level controls, such as firewall rules preventing the web server from initiating outbound connections to internal subnets, provides a robust defense-in-depth strategy that complements application-layer fixes and ensures that even if code vulnerabilities exist, their exploitation is blocked by infrastructure policies.