CVE-2025-9400 in YiFang
Summary
by MITRE • 08/25/2025
A flaw has been found in YiFang CMS up to 2.0.5. This affects the function mergeMultipartUpload of the file app/utils/base/plugin/P_file.php. This manipulation of the argument File causes unrestricted upload. Remote exploitation of the attack is possible. The exploit has been published and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
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Analysis
by VulDB Data Team • 12/11/2025
The vulnerability identified as CVE-2025-9400 represents a critical security flaw within YiFang CMS version 2.0.5 and earlier, specifically targeting the mergeMultipartUpload function located in app/utils/base/plugin/P_file.php. This function processes file upload operations and contains a significant design flaw that permits unrestricted file uploads through manipulation of the File argument parameter. The vulnerability stems from insufficient input validation and sanitization mechanisms that fail to properly verify the file type and content before processing the upload operation. Attackers can exploit this weakness by crafting malicious file uploads that bypass normal security restrictions, potentially allowing execution of arbitrary code on the affected server. The flaw exists within the core file handling functionality of the CMS, making it particularly dangerous as it affects fundamental upload operations that are commonly used throughout the platform.
The technical implementation of this vulnerability creates a direct pathway for remote code execution through unrestricted file uploads, which aligns with CWE-434 Unrestricted Upload of File with Dangerous Type. The mergeMultipartUpload function does not properly validate the file extension or content type, allowing attackers to upload malicious files such as php scripts, web shells, or other executable content. This type of vulnerability enables attackers to establish persistent access to the server, potentially leading to full system compromise. The attack vector is particularly concerning because it allows remote exploitation without requiring authentication, meaning any attacker with access to the vulnerable system can leverage this flaw. The fact that a working exploit has been published and is available in the wild significantly increases the risk profile of this vulnerability.
The operational impact of CVE-2025-9400 extends beyond simple unauthorized file uploads to encompass complete system compromise and data breaches. Organizations running affected YiFang CMS versions face potential exposure to persistent threats where attackers can establish backdoors, exfiltrate sensitive data, or use the compromised system as a launching point for further attacks within their network. The vulnerability affects the core file management capabilities of the CMS, potentially disrupting normal operations while simultaneously providing attackers with elevated privileges. Given that the vendor did not respond to early disclosure attempts, organizations may be left without official patches or mitigations, forcing them to implement emergency security measures. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1190 Exploit Public-Facing Application and T1078 Valid Accounts, as attackers can leverage the unrestricted upload capability to gain persistent access and maintain control over the compromised system.
Organizations affected by this vulnerability should immediately implement multiple layers of defense including network segmentation to limit access to the CMS, disabling unnecessary file upload functionality, and implementing strict file type validation mechanisms. The recommended mitigations include patching the affected CMS version to the latest release, implementing web application firewalls to detect and block malicious file upload attempts, and conducting comprehensive security audits of all file upload handlers within the application. Additionally, organizations should enforce strict file extension and content validation, implement proper file upload directories with restricted permissions, and establish monitoring protocols to detect suspicious file upload activities. The vulnerability demonstrates the critical importance of proper input validation and secure file handling practices in web applications, particularly in content management systems where file upload functionality is frequently utilized. Given the published exploit availability, immediate action is essential to prevent potential compromise of affected systems and protect against unauthorized access to sensitive data and infrastructure.