Shadow Servers have identified 454 vulnerable SAP NetWeaver systems affected by a critical zero-day flaw, CVE-2025-31324. This vulnerability, which has been actively exploited, allows unauthenticated attackers to upload malicious files and potentially compromise entire systems. The flaw, rated with the highest CVSS severity score of 10.0, impacts the Metadata Uploader component of SAP NetWeaver Visual Composer. The vulnerability was discovered in April 2025 during an incident response by ReliaQuest security researchers, and even fully-patched SAP installations have been targeted.
The issue lies in the “/developmentserver/metadatauploader” endpoint, which lacks proper authorization checks. This weakness enables attackers to upload JSP webshells into publicly accessible directories. The vulnerability is classified as CWE-434, “Unrestricted Upload of File with Dangerous Type,” making it particularly dangerous as it requires no authentication or user interaction. In some observed attacks, the threat actors used advanced post-exploitation tools like the Brute Ratel C4 framework and evasion techniques such as Heaven’s Gate.
This flaw specifically affects SAP NetWeaver Visual Composer, a component present in 50-70% of Java systems, according to Onapsis. Once an attacker exploits the vulnerability, they can deploy malware, establish persistent access, and exfiltrate sensitive data from the compromised systems. The ease of execution and the lack of authentication make this vulnerability extremely risky for organizations. Experts, including Vahagn Vardanian of RedRays, have emphasized its potential for complete system compromise and control by attackers.
SAP responded to the issue by releasing an emergency patch on April 24, 2025, through Security Note 3594142. Organizations are urged to apply this patch immediately or use the temporary workaround described in SAP Note 3593336. To check for vulnerabilities, organizations should verify if the endpoint is accessible without authentication, review web server logs, and monitor for unauthorized file uploads and outbound connections. Security experts stress that this vulnerability should be treated as a top priority, with timely patching and enhanced monitoring to mitigate risk.
systems and highlights the importance of securing even the most basic system functions to prevent exploitation.
