External risk intelligence

SAP S/4HANA Rule Processing Arbitrary Code Execution

CVE advisorySeverity: CRITICAL (CVSS 9.9)

CVE-2026-89107

The vulnerability exists within internal SAP S/4HANA business rule configuration functionality. While network-reachable, this component is designed for authenticated users with specific business privileges rather than public-facing internet services. Exposure is uncommon in typical deployments, as these management interfaces are generally restricted to internal users or administrative segments.

Code Injection

Halo Surface Signal: 2 out of 5 — less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This vulnerability affects SAP S/4HANA systems and could allow an authenticated attacker to execute malicious code, potentially leading to a full system compromise and significant disruption of business operations. The main concern is confirming relevance and exposure within your specific deployment.

Attackers can run custom code on affected systems.
This could lead to a complete system takeover.
Verify if your SAP S/4HANA system is exposed.

Attack Path

How an attacker could exploit the issue

An attacker with certain business privileges could craft special input that, when processed by the rule definition functionality, is treated as executable ABAP code. This allows the attacker to run their own code on the system.

Requires specific business privileges.
Triggered by specially crafted input.
Leads to full system compromise.

Live Threat

Current exploitation, exposure, and threat context

An authenticated attacker with specific business privileges could potentially execute arbitrary ABAP code within SAP S/4HANA by crafting malicious input for the rule definition functionality. This could affect the confidentiality, integrity, and availability of the affected system.

System data and ABAP code.
Input processed by rule definition functionality.
Full system compromise and data loss.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability affects SAP S/4HANA's rule definition functionality. The initial step is to identify all instances of the affected component, determine their business criticality and network reachability, and then identify the accountable application or platform owner. Remediation planning should be based on the identified risk.

Application owners must manage the issue.
Verify business criticality and reachability.
Plan remediation based on risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is SAP S/4HANA?

SAP S/4HANA is an enterprise resource planning software suite that manages core business functions like finance, supply chain, and procurement. It uses the ABAP programming language to handle complex business processes, including custom rules for data substitution and validation, which serve as the foundation for the system's operational logic.

What is the nature of the flaw in CVE-2026-89107?

This vulnerability is classified as CWE-94, or Improper Control of Generation of Code. It occurs because the software fails to properly sanitize input in its rule-definition component. Consequently, the system mistakes user-supplied data for legitimate ABAP code instructions, allowing that input to be executed directly by the underlying engine.

How is this vulnerability triggered?

An attacker must have valid credentials with specific business privileges to access the rule definition functionality. It is not triggered by public or unauthenticated web requests. The bug is activated only when these authorized users submit specially crafted input strings designed to manipulate the scripting language processed by the rule engine.

Is my SAP S/4HANA system at risk?

Halo Surface Signal indicates that this issue is unlikely to be exposed to the internet. Because the vulnerable rule-configuration interface is typically restricted to internal administrative or business segments, the primary concern is for internal users with high-level privileges rather than external, unauthenticated attackers scanning from the web.

How should I respond to this threat?

Start by identifying all SAP S/4HANA instances in your environment that utilize the Manage Substitution/Validation Rules functionality. Work with the respective application owners to verify which user roles possess the necessary privileges to access these configurations. Prioritize these systems for patching based on their business criticality and current network segmentation.

References

me.sap.com/notes/3805589

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.