CVE-2025-15426 is a vulnerability discovered in the jackying H-ui.admin web administration framework, specifically affecting versions 3.0 and 3.1. The flaw resides in the /lib/webuploader/0.1.5/server/preview.php script, which handles file uploads. Due to insufficient validation or restrictions on uploaded files, attackers can perform unrestricted uploads remotely without any authentication or user interaction. This enables adversaries to upload malicious files such as web shells or scripts, which can be executed on the server, potentially leading to full system compromise, data leakage, or pivoting within the network. The vulnerability has a CVSS 4.0 base score of 6.9, indicating medium severity, with attack vector being network-based, low attack complexity, and no privileges or user interaction required. The vendor was notified but has not issued any patches or advisories, and while no active exploitation has been reported, a public exploit code is available, increasing the risk of future attacks. The lack of patching and vendor response heightens the urgency for affected organizations to implement compensating controls. This vulnerability is particularly critical for environments where H-ui.admin is exposed to the internet or untrusted networks, as it can be exploited remotely with minimal effort.

For European organizations, exploitation of CVE-2025-15426 could lead to unauthorized remote code execution, allowing attackers to gain control over administrative web servers running H-ui.admin. This can result in data breaches, defacement, disruption of administrative functions, and lateral movement within corporate networks. Organizations in sectors such as government, finance, healthcare, and critical infrastructure that rely on H-ui.admin for internal or external administration face increased risks of operational disruption and reputational damage. The medium severity rating reflects the moderate but significant impact on confidentiality, integrity, and availability. Since no authentication is required, any exposed instance is vulnerable to automated attacks, increasing the likelihood of compromise. The absence of vendor patches means organizations must rely on internal mitigations, increasing operational overhead and risk exposure. European data protection regulations such as GDPR may impose additional legal and financial consequences if personal data is compromised due to this vulnerability.

Until an official patch is released, European organizations should implement strict file upload validation and filtering on the affected endpoint, restricting allowed file types, sizes, and content. Deploy web application firewalls (WAFs) with custom rules to detect and block malicious upload attempts targeting /lib/webuploader/0.1.5/server/preview.php. Limit network exposure of H-ui.admin interfaces by restricting access to trusted IP addresses or via VPNs. Conduct thorough logging and monitoring of upload activity to detect suspicious behavior early. Consider temporarily disabling or isolating the vulnerable upload functionality if feasible. Regularly scan systems for web shells or unauthorized files that may have been uploaded. Engage in threat hunting exercises focused on this vulnerability. Maintain up-to-date backups to enable recovery in case of compromise. Finally, monitor vendor channels for any forthcoming patches or advisories and plan for immediate deployment once available.