CVE-2026-44748: SAP NetWeaver Auth Bypass Vulnerability

CVE-2026-44748 Overview

CVE-2026-44748 is an improper signature verification vulnerability [CWE-347] in SAP NetWeaver Application Server ABAP and ABAP Platform. An authenticated attacker with normal privileges can obtain a valid signed message and submit modified signed XML documents to the verifier. The verifier accepts the tampered content as legitimate, allowing the attacker to forge identity information. Successful exploitation grants unauthorized access to sensitive user data and can disrupt normal system operations. The flaw affects confidentiality, integrity, and availability of the application.

Critical Impact

Authenticated attackers can tamper with signed XML documents to impersonate users and access sensitive data within SAP NetWeaver ABAP environments.

Affected Products

• SAP NetWeaver Application Server ABAP
• SAP ABAP Platform
• SAP systems consuming signed XML messages through the affected verifier component

Discovery Timeline

• 2026-06-09 - CVE-2026-44748 published to the National Vulnerability Database
• 2026-06-09 - Last updated in NVD database
• SAP Security Patch Day - SAP releases corrective note 3746332

Technical Details for CVE-2026-44748

Vulnerability Analysis

The vulnerability resides in the XML signature verification logic within SAP NetWeaver Application Server ABAP and ABAP Platform. The verifier fails to fully validate the relationship between the signed elements and the document content presented for processing. An attacker who already holds normal user privileges can retrieve a legitimately signed XML message produced by the system. The attacker then alters identity-bearing elements of that document while preserving the original signature reference. When the modified document is resubmitted, the verifier treats the tampered identity claims as authentic. The scope change documented in the CVSS vector reflects that exploitation impacts components beyond the vulnerable verifier itself.

Root Cause

The root cause is improper verification of cryptographic signatures, classified under [CWE-347]. The XML signature processor validates the signature value against signed references without enforcing strict binding between the signed scope and the consumed payload. This permits XML signature wrapping style manipulation where attacker-controlled elements are evaluated by application logic while signature verification operates on unmodified reference data.

Attack Vector

Exploitation requires network access and a valid low-privilege account on the target SAP system. The attacker first obtains a legitimately signed XML response or assertion from normal interaction with the system. They then craft a modified document that retains the original signed element and signature, but inserts forged identity attributes that the application layer consumes. The verifier returns a successful validation result, and the application acts upon the forged identity, granting access to data and functions outside the attacker's authorization scope. No user interaction is required.

No verified proof-of-concept code has been published for CVE-2026-44748. Refer to SAP Note #3746332 for vendor technical details.

Detection Methods for CVE-2026-44748

Indicators of Compromise

• Repeated submissions of signed XML documents from the same authenticated session with varying identity attributes
• Application audit log entries showing authorization decisions inconsistent with the authenticated user's role assignments
• Verifier success events followed by access to objects outside the requesting user's normal scope

Detection Strategies

• Correlate SAP Security Audit Log events with identity claims observed in inbound XML payloads to detect mismatches between authenticated session principal and asserted identity
• Inspect signed XML traffic for structural anomalies such as duplicated Id attributes, wrapped Signature elements, or references pointing to elements outside the document body
• Baseline expected callers of signature-protected endpoints and alert on unusual frequency or content variation in posted XML documents

Monitoring Recommendations

• Enable verbose logging on the ABAP signature verification component and forward events to a centralized SIEM for correlation
• Monitor for privilege escalation patterns where a low-privilege account suddenly accesses high-value transactions or sensitive tables
• Track outbound data flows from accounts that recently submitted signed XML documents to detect data exfiltration following identity forgery

How to Mitigate CVE-2026-44748

Immediate Actions Required

• Apply the corrective patch referenced in SAP Note #3746332 to all affected NetWeaver ABAP and ABAP Platform systems
• Review all SAP user accounts and revoke or rotate credentials for accounts showing anomalous signed XML submissions
• Restrict network exposure of signature-consuming endpoints to trusted internal segments where feasible

Patch Information

SAP has issued corrective guidance through SAP Note 3746332, published as part of SAP Security Patch Day. Administrators must authenticate to the SAP support portal to download the kernel and component updates that resolve the signature verification flaw. Apply patches to development, quality assurance, and production landscapes in sequence and validate signed XML workflows after deployment.

Workarounds

• Disable or restrict ABAP services that consume externally supplied signed XML documents until the patch is deployed
• Enforce additional application-layer checks that compare authenticated session identity against any identity claims extracted from signed XML payloads
• Limit user authorizations so that compromise of a low-privilege account cannot be leveraged into access to sensitive transactions even if identity forgery succeeds

# Configuration example
# Verify SAP Note 3746332 is applied and signature verification component is current
# (Run within SAP GUI / transaction SPAM or via command line on the SAP host)
sapcontrol -nr <instance_number> -function GetVersionInfo
# Then in SAP GUI: transaction SNOTE -> Goto -> Note Browser -> 3746332
# Confirm status: "Completely implemented"