CVE-2025-1220 is a vulnerability classified under CWE-918 (Server-Side Request Forgery) that affects PHP versions 8.1.* before 8.1.33, 8.2.* before 8.2.29, 8.3.* before 8.3.23, and 8.4.* before 8.4.10. The root cause lies in the inadequate validation of hostnames passed to functions such as fsockopen(), which do not check for embedded null characters. When a hostname contains a null byte, functions like parse_url() may parse the URL differently than fsockopen(), leading to inconsistent interpretation of the target host. This inconsistency can be exploited by attackers if the application performs security checks on the hostname using parse_url() but then initiates network connections using fsockopen() or similar functions that do not handle null bytes properly. Such a scenario can allow an attacker to bypass access controls and make unauthorized internal or external network requests, characteristic of SSRF attacks. The vulnerability does not require authentication or user interaction but has a high attack complexity, limiting its exploitation potential. No known exploits have been reported in the wild, and no official patches were linked at the time of publication. The CVSS v3.1 base score is 3.7, reflecting a low severity primarily due to limited confidentiality impact and the complexity of exploitation.

For European organizations, this vulnerability poses a moderate risk primarily to web applications and services running on affected PHP versions. SSRF vulnerabilities can be leveraged to access internal network resources, potentially exposing sensitive data or enabling further lateral movement within corporate networks. Although the CVSS score is low, the impact depends heavily on the context of the vulnerable application, such as whether it processes untrusted user input in network-related functions. Organizations with PHP-based web infrastructure, especially those exposing internal APIs or services, could face risks of unauthorized internal resource access or information disclosure. Given the widespread use of PHP in Europe’s public and private sectors, including government portals, e-commerce, and financial services, the vulnerability could be exploited to bypass security controls if not mitigated. However, the high attack complexity and lack of known exploits reduce the immediate threat level. Still, failure to address this issue could lead to targeted SSRF attacks, particularly in environments where internal network segmentation or access controls are weak.

European organizations should prioritize updating PHP to the fixed versions (8.1.33, 8.2.29, 8.3.23, or 8.4.10 and later) as soon as patches become available. Until patches are applied, developers should implement strict input validation and sanitization to reject hostnames containing null characters or other suspicious input before passing them to network functions like fsockopen(). Additionally, security checks should be performed on the exact data used for network connections, avoiding discrepancies between validation and execution. Employing web application firewalls (WAFs) with rules to detect and block SSRF patterns can provide an additional layer of defense. Network segmentation and restricting outbound connections from web servers to only necessary destinations can limit the impact of potential SSRF exploitation. Regular code audits focusing on URL parsing and network request logic are recommended to identify similar inconsistencies. Monitoring logs for unusual outbound requests from web applications can help detect exploitation attempts early.