Public Exploit Released for Critical SAP NetWeaver Flaw

CVE-2025-31324 is a critical (CVSS 9.8) unrestricted file upload flaw (CWE-434) in the Visual Composer Metadata Uploader component of SAP NetWeaver, which lacks proper authorization. An unauthenticated attacker can send crafted upload requests over the network to the Metadata Uploader endpoint and plant malicious executable binaries, such as webshells, on the host. Executing the uploaded files yields remote code execution with full impact on confidentiality, integrity, and availability, enabling system compromise, lateral movement, and ransomware deployment. Any organization running the affected SAP NetWeaver component is at risk, with the greatest exposure for instances reachable from the internet. Exploitation is confirmed in the wild: the flaw was added to CISA KEV on 2025-04-29, a public PoC exists, and researchers and media report active attacks, including by Chinese-linked actors deploying Golang-based implants on Linux systems and known ransomware use, often chained with CVE-2025-42999.

Do: Apply SAP's patch for CVE-2025-31324 (released in the April 2025 security updates) and follow the vendor mitigation instructions per CISA KEV/BOD 22-01 requirements. As interim mitigation, restrict or disable the Visual Composer Metadata Uploader endpoint and ensure it is not reachable from the internet; also patch the related CVE-2025-42999 since the flaws are being chained. Check affected hosts for uploaded webshells, Golang-based implants, and signs of ransomware activity.

CVE-2025-42999 is an insecure deserialization flaw (CWE-502) in the Visual Composer Metadata Uploader component of SAP NetWeaver. It is triggered when a privileged user uploads untrusted or malicious content to the Metadata Uploader, which the application then deserializes; on its own the flaw requires high-privilege access, but attackers commonly chain it with the separately tracked unauthenticated upload flaw CVE-2025-31324 in the same component. Successful exploitation can yield remote code execution and full compromise of the host's confidentiality, integrity, and availability, with impact beyond the vulnerable component (CVSS scope changed, 9.1 critical). Any organization running SAP NetWeaver with the Visual Composer Metadata Uploader enabled, especially internet-facing application servers, is affected. Exploitation is confirmed in the wild: CISA added it to the Known Exploited Vulnerabilities catalog on 2025-05-15 with known ransomware use, and reporting links active attacks to ransomware groups (BianLian and RansomExx deploying the PipeMagic trojan) and to Chinese-linked APTs exploiting the sibling CVE-2025-31324.

Do: Apply SAP's security patches addressing CVE-2025-42999 together with the companion CVE-2025-31324 in the same Visual Composer Metadata Uploader, per vendor instructions, or restrict/disable access to the Metadata Uploader endpoint if patching is delayed. Given confirmed ransomware use (BianLian, RansomExx) and PipeMagic trojan deployments, review upload and authentication logs on NetWeaver servers and hunt for signs of compromise and post-exploitation activity. U.S. federal agencies must follow CISA BOD 22-01 guidance: apply mitigations by the KEV remediation due date or discontinue use of affected instances.