CVE-2025-41347 is a vulnerability classified under CWE-434 (Unrestricted Upload of File with Dangerous Type) affecting Informática del Este's WinPlus software, specifically version 24.11.27. The flaw resides in the file upload functionality exposed at the endpoint '/WinplusPortal/ws/sWinplus.svc/json/uploadfile', which fails to properly restrict the types of files that can be uploaded. This allows an attacker to upload arbitrary files, including malicious webshells, by sending a crafted POST request. The vulnerability requires low privileges (PR:L) but no user interaction (UI:N) and no authentication tokens beyond low-level privileges, making it relatively easy to exploit in environments where an attacker has some authenticated access. The CVSS 4.0 score of 8.7 reflects the high impact on confidentiality, integrity, and availability, with the potential for complete system compromise. The vulnerability is network exploitable (AV:N) and does not require complex attack conditions (AC:L). No patches or fixes have been published yet, and there are no known exploits in the wild, but the risk remains significant due to the nature of the vulnerability. The vulnerability was reserved in April 2025 and published in November 2025, indicating recent discovery and disclosure. The lack of input validation and insufficient file type restrictions are the root causes, which are common issues in web application security. Attackers leveraging this vulnerability could deploy webshells to execute arbitrary commands, move laterally, or exfiltrate data.

For European organizations, exploitation of CVE-2025-41347 could lead to severe consequences including unauthorized remote code execution, data breaches, and disruption of critical services. Organizations using WinPlus in sectors such as manufacturing, logistics, or public administration could face operational downtime and loss of sensitive information. The ability to upload webshells enables attackers to maintain persistent access, escalate privileges, and potentially pivot to other internal systems. This could result in regulatory non-compliance, especially under GDPR, due to data confidentiality breaches. The high severity and network exploitability mean attackers can compromise systems remotely, increasing the attack surface. Additionally, the absence of patches increases the window of exposure. European entities relying on this software for business-critical operations are particularly vulnerable to espionage, sabotage, or ransomware attacks stemming from this flaw.

Given the absence of official patches, European organizations should implement immediate compensating controls. These include restricting access to the vulnerable upload endpoint via network segmentation and firewall rules, limiting access to trusted users only. Implement web application firewalls (WAFs) with custom rules to detect and block attempts to upload executable or script files, especially those resembling webshells. Conduct thorough input validation and enforce strict file type whitelisting at the application layer, if possible through configuration or custom development. Monitor logs for unusual POST requests to the upload endpoint and establish alerting for suspicious file uploads. Employ multi-factor authentication and least privilege principles to reduce the risk of low-privilege accounts being compromised. Regularly audit and review user permissions and uploaded files. Prepare incident response plans specifically addressing webshell detection and removal. Finally, maintain close communication with Informática del Este for forthcoming patches and apply them promptly once available.