CVE-2025-5498 is a deserialization vulnerability identified in slackero phpwcms versions up to 1.9.45 and 1.10.8. The flaw exists in the Custom Source Tab component, specifically within the file include/inc_lib/content/cnt21.readform.inc.php, affecting the functions file_get_contents and is_file. The vulnerability arises from improper handling of the 'cpage_custom' argument, which can be manipulated to trigger unsafe deserialization of user-supplied data. This deserialization flaw allows an attacker to remotely execute arbitrary code or manipulate application logic without authentication, as the attack vector is network accessible and does not require privileges. The vulnerability has a CVSS 4.0 score of 5.1, indicating medium severity, with an attack vector of network, low attack complexity, no privileges required, but requiring user interaction. The impact on confidentiality, integrity, and availability is low, but the exploitability is facilitated by the lack of authentication and network accessibility. Although no known exploits are currently observed in the wild, the public disclosure of the exploit increases the risk of exploitation. The vendor has addressed the issue in versions 1.9.46 and 1.10.9, and upgrading to these or later versions is recommended to remediate the vulnerability.

For European organizations using slackero phpwcms, this vulnerability poses a moderate risk. Exploitation could lead to unauthorized code execution or manipulation of content management functions, potentially compromising website integrity and availability. While the confidentiality impact is low, attackers could deface websites, inject malicious content, or disrupt services, affecting business reputation and user trust. Organizations in sectors relying heavily on web presence, such as e-commerce, media, and government services, may experience operational disruptions. The medium severity and requirement for user interaction somewhat limit the threat scope; however, the remote exploitability and public availability of the exploit code increase the urgency for mitigation. Failure to patch could lead to targeted attacks exploiting this vulnerability, especially in environments where phpwcms is used without additional security controls.

Beyond upgrading to phpwcms versions 1.9.46 or 1.10.9, organizations should implement several practical measures: 1) Conduct a thorough inventory of phpwcms instances to identify affected versions. 2) Apply strict input validation and sanitization on all user-supplied parameters, especially those related to 'cpage_custom', to prevent malicious payloads from reaching deserialization routines. 3) Employ Web Application Firewalls (WAFs) with custom rules to detect and block suspicious deserialization patterns or anomalous requests targeting the vulnerable endpoint. 4) Monitor logs for unusual activity related to the Custom Source Tab component and file_get_contents/is_file function calls. 5) Restrict access to the vulnerable component by IP whitelisting or network segmentation where feasible. 6) Implement runtime application self-protection (RASP) solutions to detect and prevent exploitation attempts in real time. 7) Educate development and security teams about secure deserialization practices to avoid similar vulnerabilities in custom code.