CVE-2025-13815 identifies a security weakness in moxi159753 Mogu Blog v2, specifically in versions 5.0 through 5.2. The vulnerability is located in an unspecified function within the /file/pictures endpoint, where the 'filedatas' parameter is manipulated to allow unrestricted file uploads. This lack of proper input validation or sanitization permits remote attackers to upload arbitrary files, potentially including malicious scripts or executables, without requiring authentication or user interaction. The vulnerability is exploitable over the network with low complexity, as no privileges or user involvement are needed. The vendor was notified early but has not issued any patches or advisories, and no public exploit code is currently known to be in active use. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no authentication required (AT:N), no user interaction (UI:N), and low impact on confidentiality, integrity, and availability (VC:L, VI:L, VA:L). This suggests that while the vulnerability is moderately severe, exploitation could lead to unauthorized file uploads that may be leveraged for further attacks such as remote code execution, defacement, or data theft. The absence of vendor response and patch availability increases the risk for users of this blogging platform.

For European organizations utilizing Mogu Blog v2, this vulnerability poses a tangible risk of unauthorized server access and compromise. Attackers could upload web shells or malicious payloads, leading to potential data breaches, defacement, or disruption of services. Given the medium severity, the impact on confidentiality, integrity, and availability is moderate but could escalate if combined with other vulnerabilities or misconfigurations. Organizations hosting sensitive or regulated data on affected platforms may face compliance and reputational risks. The lack of vendor patches means organizations must rely on alternative mitigation strategies, increasing operational overhead. The threat is particularly relevant for small to medium enterprises and public-facing websites using this blogging software in Europe, where regulatory frameworks such as GDPR impose strict data protection requirements. Failure to address this vulnerability could result in legal and financial consequences in addition to technical damage.

Since no official patches are available, European organizations should implement immediate compensating controls. These include restricting access to the /file/pictures endpoint via web application firewalls (WAFs) or reverse proxies to block unauthorized upload attempts. Input validation and file type restrictions should be enforced at the server or application level if possible. Monitoring and logging upload activities can help detect suspicious behavior early. Organizations should consider isolating the blogging platform in a segmented network environment with limited privileges to minimize potential damage. Regular backups and incident response plans should be updated to address potential exploitation scenarios. If feasible, migrating to alternative blogging platforms with active security support is advisable. Additionally, organizations should engage with the vendor or community to encourage patch development and share threat intelligence related to this vulnerability.