CVE-2026-0506: SAP ABAP Auth Bypass Vulnerability

CVE-2026-0506 Overview

CVE-2026-0506 is a Missing Authorization Check vulnerability (CWE-862) affecting SAP Application Server ABAP and ABAP Platform. The vulnerability allows an authenticated attacker to misuse an RFC (Remote Function Call) function to execute form routines (FORMs) within the ABAP system without proper authorization validation. Successful exploitation enables attackers to write or modify data accessible via FORMs and invoke system functionality exposed through these routines.

Critical Impact

This vulnerability allows authenticated attackers to bypass authorization controls, potentially leading to unauthorized data modification and system disruption with high impact on integrity and availability.

Affected Products

• SAP Application Server ABAP
• SAP ABAP Platform
• SAP NetWeaver Application Server ABAP

Discovery Timeline

• 2026-01-13 - CVE-2026-0506 published to NVD
• 2026-01-13 - Last updated in NVD database

Technical Details for CVE-2026-0506

Vulnerability Analysis

This vulnerability stems from insufficient authorization checks within RFC-enabled function modules in the SAP ABAP environment. When an authenticated user calls certain RFC functions, the system fails to properly verify whether the caller has the necessary authorization to execute the associated form routines (FORMs). This missing authorization check creates a gap that allows attackers to invoke functionality they should not have access to.

The impact focuses primarily on integrity and availability, as attackers can modify data and invoke system operations. Confidentiality remains unaffected because the vulnerability does not expose protected data for reading—it only enables write operations and function execution through the unauthorized FORM invocations.

Root Cause

The root cause is a Missing Authorization Check (CWE-862) in the RFC function module implementation. The vulnerable code path allows authenticated users to execute FORM routines without verifying whether the user possesses the required authorization objects. SAP systems typically rely on authorization objects and profiles to control access, but this implementation fails to perform the necessary AUTHORITY-CHECK calls before executing sensitive operations within the FORM routines.

Attack Vector

The attack is network-accessible and requires authentication to the SAP system. An attacker with valid credentials (even with low privileges) can exploit this vulnerability by:

1. Establishing an RFC connection to the vulnerable SAP system
2. Calling the affected RFC function module with crafted parameters
3. Specifying FORM routine names to be executed
4. Bypassing authorization checks that would normally restrict access
5. Writing or modifying data through the unauthorized FORM execution

The vulnerability exploits the trust relationship between RFC calls and internal FORM routine execution, where the intermediate authorization validation is missing.

Detection Methods for CVE-2026-0506

Indicators of Compromise

• Unusual RFC function calls from users with limited authorizations
• Unexpected modifications to data accessible through FORM routines
• Anomalous system log entries showing FORM routine execution from unexpected sources
• Increased RFC gateway activity from authenticated sessions

Detection Strategies

• Monitor SAP Security Audit Log (SM21) for unauthorized RFC function calls
• Review System Log (ST22) for abnormal FORM routine executions
• Implement SAP Solution Manager alerting for suspicious RFC patterns
• Configure SIEM rules to correlate RFC activity with user authorization profiles

Monitoring Recommendations

• Enable verbose logging for RFC function module calls in transaction SM59
• Configure SAP Gateway logging to capture RFC request details
• Set up alerts for RFC calls to sensitive function modules from non-administrative users
• Regularly audit user authorizations against actual RFC usage patterns

How to Mitigate CVE-2026-0506

Immediate Actions Required

• Apply the security patch referenced in SAP Note #3688703
• Review RFC-enabled function modules for proper authorization checks
• Restrict RFC access using authorization objects S_RFC and S_RFCACL
• Audit user authorizations and remove unnecessary RFC privileges

Patch Information

SAP has released a security update to address this vulnerability. Administrators should apply the patch detailed in SAP Note #3688703. The patch implements proper authorization checks before FORM routine execution within the affected RFC function modules. For complete patch day information, refer to the SAP Security Patch Day Update.

Workarounds

• Implement strict RFC authorization controls using S_RFC authorization object
• Disable or restrict access to the vulnerable RFC function module until patching is complete
• Use SAP Gateway ACL (Access Control List) to limit RFC connections to trusted sources
• Enable RFC call monitoring and implement real-time alerting for suspicious activity

* Temporary mitigation: Add authorization check in affected code
* Apply before FORM routine execution
AUTHORITY-CHECK OBJECT 'S_RFC'
  ID 'RFC_TYPE' FIELD 'FUNC'
  ID 'RFC_NAME' FIELD lv_function_name
  ID 'ACTVT' FIELD '16'.
IF sy-subrc <> 0.
  RAISE EXCEPTION TYPE cx_authorization_error.
ENDIF.