CVE-2026-27673: SAP S/4HANA Auth Bypass Vulnerability

CVE-2026-27673 Overview

CVE-2026-27673 is a Missing Authorization vulnerability (CWE-862) affecting SAP S/4HANA in both Private Cloud and On-Premise deployments. Due to a missing authorization check, an authenticated user can delete files on the operating system and gain unauthorized control over file operations. This vulnerability allows attackers with low privileges to impact system integrity and availability through unauthorized file manipulation.

Critical Impact

Authenticated users can bypass authorization controls to delete arbitrary files on the operating system, potentially disrupting SAP S/4HANA operations and compromising data integrity.

Affected Products

• SAP S/4HANA (Private Cloud)
• SAP S/4HANA (On-Premise)

Discovery Timeline

• April 14, 2026 - CVE-2026-27673 published to NVD
• April 14, 2026 - Last updated in NVD database

Technical Details for CVE-2026-27673

Vulnerability Analysis

This vulnerability stems from a Missing Authorization (CWE-862) flaw in SAP S/4HANA's file operation handling. The application fails to properly verify whether authenticated users have the necessary permissions before allowing file deletion operations on the underlying operating system.

The attack requires network access and an authenticated session with low privileges. While the attack complexity is high due to specific conditions that must be met for successful exploitation, the changed scope indicates that the vulnerability can affect resources beyond the vulnerable component itself. The impact is primarily focused on integrity and availability rather than confidentiality, as successful exploitation enables file deletion rather than data exfiltration.

Root Cause

The root cause is a missing authorization check in SAP S/4HANA's file management functionality. The application does not properly validate whether the authenticated user possesses adequate privileges to perform file deletion operations. This allows users with basic authentication to the system to execute file operations that should be restricted to administrative or specially privileged accounts.

Attack Vector

The vulnerability is exploitable over the network by authenticated users. An attacker would need to:

1. Obtain valid authentication credentials to the SAP S/4HANA system
2. Identify the vulnerable file operation endpoint or functionality
3. Craft requests that bypass the missing authorization check
4. Execute unauthorized file deletion operations on the operating system

The attack does not require user interaction, making it potentially automatable once authentication is obtained. The changed scope (S:C) indicates that successful exploitation can impact resources managed by other security authorities beyond the vulnerable SAP component.

The vulnerability mechanism involves the application processing file deletion requests without verifying proper authorization. Technical details are available in SAP Note #3703813.

Detection Methods for CVE-2026-27673

Indicators of Compromise

• Unexpected file deletion events in SAP S/4HANA application logs
• Anomalous file system activity from SAP service accounts
• Unauthorized access attempts to file management functions by non-administrative users
• System instability caused by deletion of critical configuration or data files

Detection Strategies

• Monitor SAP Security Audit Logs (SM21) for unauthorized file operation attempts
• Implement file integrity monitoring (FIM) on critical SAP directories and configuration files
• Configure alerts for bulk file deletion activities or deletions of protected system files
• Review authorization object usage patterns, particularly those related to file operations

Monitoring Recommendations

• Enable comprehensive logging for file system operations within SAP S/4HANA
• Correlate SAP application logs with operating system file access logs
• Establish baselines for normal file operation patterns to detect anomalous deletion activities
• Deploy SIEM rules to alert on file deletion attempts by users without appropriate authorization roles

How to Mitigate CVE-2026-27673

Immediate Actions Required

• Apply the security patch documented in SAP Note #3703813
• Review and restrict user authorizations related to file operations in SAP S/4HANA
• Audit user accounts with access to file management functionality
• Implement additional access controls at the operating system level for critical directories

Patch Information

SAP has released a security update to address this vulnerability. Administrators should consult SAP Note #3703813 for detailed patch information and apply the fix according to the guidance provided in the SAP Security Patch Day advisory.

Workarounds

• Restrict access to file management functionality to only essential administrative users
• Implement network segmentation to limit access to SAP S/4HANA systems from trusted networks only
• Enable enhanced monitoring and alerting for file operations pending patch deployment
• Review and harden authorization objects related to file system access in transaction SU24 and PFCG

Consult the official SAP documentation and SAP Note #3703813 for vendor-recommended workarounds and configuration guidance.