CVE-2026-23687 is a vulnerability classified under CWE-347 (Improper Verification of Cryptographic Signature) found in SAP NetWeaver Application Server ABAP and ABAP Platform across numerous SAP_BASIS versions ranging from 700 to 918. The vulnerability allows an authenticated attacker with normal user privileges to intercept or obtain a valid signed XML message and then modify the signed content before sending it to the signature verifier. Due to improper cryptographic signature verification, the system may accept these tampered XML documents as legitimate, leading to acceptance of falsified identity information. This can result in unauthorized access to sensitive user data and potentially disrupt normal system functionality. The vulnerability does not require user interaction and can be exploited remotely over the network, with low attack complexity. The CVSS v3.1 base score is 8.8, reflecting high confidentiality, integrity, and availability impacts. Although no public exploits have been reported yet, the vulnerability poses a significant risk due to the critical role SAP NetWeaver plays in enterprise resource planning and business-critical operations. The flaw stems from inadequate cryptographic validation logic within the SAP signature verification process, allowing attackers to bypass signature integrity checks on XML documents.

The potential impact of CVE-2026-23687 is substantial for organizations worldwide that rely on SAP NetWeaver AS ABAP and ABAP Platform. Successful exploitation can lead to unauthorized disclosure of sensitive user data, compromising confidentiality. Integrity is severely affected as attackers can manipulate signed XML documents to falsify identity information, potentially enabling privilege escalation or fraudulent transactions. Availability may also be disrupted if attackers interfere with normal system operations or cause denial of service conditions. Given SAP's widespread use in large enterprises for critical business processes such as finance, supply chain, and human resources, this vulnerability could lead to significant operational disruptions, financial losses, regulatory compliance violations, and reputational damage. The requirement for only normal authenticated privileges lowers the barrier for exploitation, increasing the risk from insider threats or compromised user accounts. Organizations without timely remediation may face increased risk of targeted attacks, data breaches, and systemic compromise.

To mitigate CVE-2026-23687, organizations should prioritize applying official SAP security patches as soon as they become available for the affected SAP_BASIS versions. In the absence of patches, implement strict access controls to limit authenticated user privileges and monitor for unusual activities involving signed XML document processing. Employ network segmentation to isolate SAP systems and restrict access to trusted administrators only. Enable detailed logging and audit trails for signature verification processes to detect potential tampering attempts. Conduct regular integrity checks on critical XML documents and validate cryptographic signatures using out-of-band verification methods where feasible. Educate users and administrators about the risks of this vulnerability and enforce strong authentication mechanisms to reduce the risk of credential compromise. Additionally, consider deploying Web Application Firewalls (WAFs) with custom rules to detect and block malformed or suspicious XML payloads targeting signature verification. Collaborate with SAP support and security teams to stay informed about updates and recommended best practices.