CVE-2026-2665 identifies a security flaw in the huanzi-qch base-admin software, a component used for administrative functions, where the Upload method in SysFileController.java improperly handles the File argument. This flaw permits an attacker to upload arbitrary files without restrictions, bypassing typical security controls that prevent malicious file uploads. The vulnerability is remotely exploitable without requiring authentication or user interaction, increasing its risk profile. The affected component is part of a JSP parser, indicating that uploaded files could potentially be executed on the server, leading to remote code execution or persistent backdoors. The product employs continuous delivery with rolling releases, which means affected versions are not clearly delineated, and no official patches or version updates have been publicly released. Although no active exploitation has been confirmed, the availability of public exploits raises the risk of imminent attacks. The CVSS 4.0 score of 5.3 reflects a medium severity, factoring in the ease of remote exploitation but limited scope and impact due to some privileges required (PR:L). The lack of vendor response further complicates mitigation efforts, emphasizing the need for proactive defensive measures.

For European organizations, this vulnerability poses a significant risk, especially for those using huanzi-qch base-admin in critical administrative or operational environments. Successful exploitation could lead to unauthorized file uploads, enabling attackers to deploy web shells, malware, or ransomware, potentially compromising confidentiality, integrity, and availability of systems. This could result in data breaches, service outages, or lateral movement within networks. Given the remote and unauthenticated nature of the exploit, attackers can target exposed interfaces over the internet or internal networks. The continuous delivery model and absence of patches increase exposure duration. Organizations in sectors with high regulatory requirements (e.g., finance, healthcare, government) face heightened compliance risks and potential fines under GDPR if personal data is compromised. Additionally, the lack of vendor responsiveness may delay remediation, increasing the window for attackers to exploit this vulnerability.

European organizations should immediately audit their environments to identify deployments of huanzi-qch base-admin, focusing on versions around the commit 57a8126bb3353a004f3c7722089e3b926ea83596. Until an official patch is available, implement strict network segmentation and firewall rules to restrict access to the Upload functionality, limiting it to trusted internal IPs only. Employ Web Application Firewalls (WAFs) with custom rules to detect and block suspicious file upload attempts, especially those containing executable code or unusual file types. Conduct thorough input validation and sanitization at the application level if possible, adding additional checks on file types, sizes, and content. Monitor logs for anomalous upload activities and establish alerting mechanisms. Consider deploying runtime application self-protection (RASP) tools to detect exploitation attempts in real time. Engage with the vendor or community to track patch releases and apply updates promptly. Finally, prepare incident response plans specific to web shell or malware infections resulting from this vulnerability.