Description

SAP NetWeaver Message Server does not sufficiently validate the authenticity of internal application server components during registration. An unauthenticated attacker with network access to the affected service could exploit this weakness to register an unauthorized component and potentially perform unauthorized actions within the application environment, resulting in a high impact on the confidentiality, integrity, and availability of the affected system.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-09-08T01:17:51.080Z",
  "pubdate": "2026-09-08T01:17:51.080Z",
  "executiveSummary": "This vulnerability concerns a lack of cryptographic or authentication-based validation in the SAP NetWeaver Message Server when handling component registration requests.\nThe vulnerability allows an unauthenticated, network-adjacent attacker to register a malicious or unauthorized application server component.\nBy successfully masquerading as a legitimate component, an attacker can manipulate the internal cluster state and perform unauthorized administrative or operational actions.\nThe impact includes full compromise of the confidentiality, integrity, and availability of the affected SAP environment.\nThe risk is critical due to the lack of required authentication for the registration process, which effectively bypasses the trust model established for internal SAP infrastructure.\nExploitation requires network access to the Message Server service, which typically runs on ports associated with the SAP message server protocol (e.g., 39xx).\nOrganizations relying on SAP NetWeaver are advised to restrict network access to the message server ports to trusted internal infrastructure components only.",
  "technicalDetails": "The vulnerability originates within the SAP NetWeaver Message Server's registration mechanism. The Message Server serves as the central orchestration point for SAP application servers, maintaining a registry of active components to facilitate internal communication and load balancing.\nThe root cause is a failure to enforce mutual authentication or cryptographic signature verification during the component registration handshake. The Message Server blindly trusts registration requests sent to it, provided they adhere to the expected communication protocol.\nThe attack flow begins when an attacker, positioned within the same network segment as the target SAP Message Server, crafts a malicious registration request using the SAP message server protocol. Because the Message Server does not validate the source identity, it accepts the attacker's server as a legitimate, authorized participant in the internal SAP cluster.\nOnce the malicious component is registered, the attacker can influence the cluster topology and intercept internal communications. The Message Server will begin routing requests intended for valid internal components to the attacker-controlled component, effectively facilitating a man-in-the-middle position for inter-process communication.\nFurthermore, by presenting as a legitimate component, the attacker can leverage the privileges inherently granted to internal application servers. This allows for the execution of unauthorized actions within the broader SAP environment, such as accessing sensitive business data, modifying critical configuration parameters, or triggering administrative functions reserved for internal system components.\nThe lack of authentication requirements means that any actor capable of initiating a TCP/IP connection to the Message Server port can trigger this vulnerability. This bypasses traditional security controls that assume the internal network is secure and that all participating nodes are pre-authorized.\nPost-exploitation impact is severe, as the attacker effectively becomes part of the application server cluster. This grants them the ability to masquerade as trusted entities, manipulate traffic distribution, and potentially gain administrative control over the application environment without the need for application-level credentials."
}