CVE-2026-23687 in NetWeaver AS ABAP and ABAP Platform
Summary
by MITRE • 02/10/2026
SAP NetWeaver Application Server ABAP and ABAP Platform allows an authenticated attacker with normal privileges to obtain a valid signed message and send modified signed XML documents to the verifier. This may result in acceptance of tampered identity information, unauthorized access to sensitive user data and potential disruption of normal system usage.
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Analysis
by VulDB Data Team • 02/18/2026
CVE-2026-23687 represents a critical security vulnerability within SAP NetWeaver Application Server ABAP and ABAP Platform that exploits weaknesses in the digital signature verification process. This vulnerability enables authenticated attackers with standard user privileges to manipulate signed XML documents by obtaining valid signatures and subsequently sending modified documents to the system's verifier. The flaw resides in the cryptographic validation mechanisms that should ensure document integrity and authenticity, creating a pathway for malicious actors to bypass security controls through crafted tampering of signed messages.
The technical implementation of this vulnerability stems from insufficient validation of XML signature integrity within the SAP NetWeaver environment. Attackers can leverage this weakness to generate modified XML documents that contain valid signatures, effectively circumventing the expected security checks. This occurs because the system's signature verification process fails to properly validate that the signed content matches the expected document structure and data. The vulnerability is particularly concerning as it operates at the application layer and requires minimal privileges to exploit, making it accessible to users who normally should not have the capability to manipulate system security controls. The underlying issue aligns with CWE-347, which addresses improper verification of cryptographic signatures, and represents a significant deviation from the expected behavior of secure signature validation protocols.
The operational impact of CVE-2026-23687 extends beyond simple data integrity concerns to encompass potential unauthorized access to sensitive user information and system disruption. When attackers successfully exploit this vulnerability, they can manipulate identity information within signed documents, potentially gaining access to user accounts, personal data, and system resources that should remain protected. The ability to send tampered signed documents to the verifier creates opportunities for privilege escalation and lateral movement within the network. This vulnerability directly impacts the integrity and authenticity guarantees that digital signatures are designed to provide, potentially allowing attackers to impersonate legitimate users or systems. The disruption of normal system usage occurs through the compromise of trust relationships that are fundamental to the security architecture of the SAP environment.
Organizations should implement immediate mitigations including enhanced signature validation procedures, regular security assessments of XML processing components, and monitoring for suspicious signature patterns. The vulnerability demonstrates the importance of maintaining strict cryptographic validation processes and implementing defense-in-depth strategies that go beyond basic authentication mechanisms. Security teams should focus on strengthening the XML signature validation logic to ensure that any modifications to signed content are properly detected and rejected. Additionally, implementing network segmentation and access controls can help limit the potential impact of successful exploitation attempts. This vulnerability highlights the necessity of adhering to security frameworks such as the ATT&CK framework's defense evasion techniques and emphasizes the critical need for proper cryptographic implementation practices that prevent signature forgery and tampering scenarios.