CVE-2025-13815 identifies an unrestricted file upload vulnerability in the moxi159753 Mogu Blog v2 software, specifically affecting versions 5.0 through 5.2. The vulnerability arises from improper validation or sanitization of the 'filedatas' parameter in the /file/pictures endpoint, allowing an attacker to upload arbitrary files remotely without authentication or user interaction. This flaw can be exploited to upload malicious scripts or executables, potentially leading to remote code execution, data tampering, or denial of service. The CVSS 4.0 base score is 5.3, reflecting medium severity due to the lack of authentication requirements and ease of exploitation, but limited impact scope and partial confidentiality, integrity, and availability impact. The vendor has not issued any patches or responses despite early notification, and no known active exploitation has been reported, though proof-of-concept exploits are publicly available. This vulnerability poses a risk to any deployment of Mogu Blog v2 exposed to the internet, especially in environments where uploaded files are executed or accessible by other users. The absence of vendor mitigation increases the urgency for organizations to apply alternative security measures.

For European organizations using Mogu Blog v2, this vulnerability could lead to unauthorized file uploads that may compromise web server integrity, enable remote code execution, or facilitate further attacks such as data theft or service disruption. The impact on confidentiality includes potential exposure of sensitive data if attackers upload scripts to access backend information. Integrity could be compromised by altering website content or injecting malicious code. Availability may be affected if attackers upload files that disrupt service or consume resources. Given the medium severity and ease of exploitation without authentication, attackers could leverage this vulnerability to gain footholds in affected systems. Organizations relying on this blogging platform for public-facing websites or internal communications are at risk, particularly if no compensating controls are in place. The lack of vendor patches means the threat persists until mitigations are implemented, increasing potential exposure time.

Since no official patches are available, European organizations should implement the following specific mitigations: 1) Restrict file upload types strictly to safe formats (e.g., images only) using server-side validation and MIME type checks. 2) Employ a web application firewall (WAF) with rules to detect and block suspicious upload attempts targeting the /file/pictures endpoint. 3) Isolate the upload directory with minimal permissions and disable execution rights to prevent uploaded files from being executed as code. 4) Monitor server logs and file upload directories for anomalous or unexpected files and patterns. 5) Consider deploying virtual patching techniques or custom filters to sanitize inputs related to file uploads. 6) If feasible, migrate to alternative blogging platforms with active security support or earlier patched versions. 7) Conduct regular security audits and penetration testing focused on file upload functionalities. 8) Educate administrators about the risks and signs of exploitation attempts related to this vulnerability.