External risk intelligence

SAP Kernel RFC Protocol Validation Memory Corruption Leads to High Impact

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-27671

The vulnerability involves the SAP Kernel and Application Server ABAP. While these components are critical, they are typically deployed within internal business networks or protected by enterprise firewalls. While RFC requests could theoretically be reachable if misconfigured, they are not standard public-facing web or gateway services designed for direct internet exposure in common deployments.

Halo Surface Signal: 3 out of 5 — possibly public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in the SAP Kernel within SAP NetWeaver and ABAP Platform. This flaw could allow an unauthenticated attacker to corrupt memory by sending a specially crafted request, potentially impacting the confidentiality, integrity, and availability of the application. The main concern at this stage is confirming the relevance and exposure of these SAP components within our environment.

Unauthenticated attackers can corrupt SAP memory.
SAP systems are critical for core business operations.
Confirm relevance and exposure of affected SAP systems.

Attack Path

How an attacker could exploit the issue

An unauthenticated attacker could send a specially crafted RFC request to the SAP Application Server ABAP. This request exploits weaknesses in how the SAP Kernel handles RFC protocols, leading to memory corruption. If successful, this could significantly compromise the confidentiality, integrity, and availability of the affected application.

No authentication required.
Crafted RFC request.
High impact to confidentiality, integrity, availability.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could affect the confidentiality, integrity, and availability of SAP Application Server ABAP. An unauthenticated attacker could send a specially crafted RFC request, exploiting memory management flaws to cause memory corruption. This could lead to a high impact on the affected system.

SAP Application Server ABAP data and services.
Via crafted RFC requests over the network.
High impact on confidentiality, integrity, availability.

Operational Fix

Recommended remediation, mitigation, and detection steps

This SAP Kernel vulnerability requires immediate attention from teams responsible for SAP NetWeaver and ABAP Platform. The first practical step is to identify all instances of the affected SAP Kernel, confirm their reachability and business criticality, and then locate the accountable system owner to plan remediation.

SAP Basis and Application teams own the issue.
Verify RFC accessibility and business criticality.
Plan remediation during the next maintenance window.

Supplementary metadata

CVSS vector

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Frequently asked questions

What is the SAP Kernel and its role in my environment?

The SAP Kernel acts as the core engine of the SAP Application Server ABAP, which powers SAP NetWeaver and ABAP platforms. It functions as the underlying interface between the SAP software and the host operating system, managing critical tasks like process execution, memory allocation, and data communication. Because it supports core business processes, the kernel is essential for the stability and operation of the entire SAP application suite.

What does memory corruption mean in CVE-2026-27671?

This CVE involves a weakness classified as CWE-121, or stack-based buffer overflow. In plain terms, the SAP Kernel fails to properly validate incoming Remote Function Call (RFC) data. When an attacker sends a specifically designed request, the system may write data beyond its intended memory space. This corruption can confuse the application, potentially allowing unauthorized data access or causing the system to crash and become unavailable.

How is this vulnerability triggered?

An attacker triggers this flaw by sending a crafted RFC request directly to the SAP Application Server ABAP. Crucially, the system does not require any authentication to process these requests, meaning an attacker does not need a user account to attempt the exploit. This vulnerability is not triggered by standard, legitimate business traffic; it specifically requires malformed data designed to exploit the memory management logic errors.

Is my SAP instance reachable from the internet?

According to Halo Surface Signal, these components are typically deployed within internal networks and protected by firewalls. While the vulnerability is network-based, these SAP services are rarely intended for direct internet exposure. You should assess if your specific SAP instances have any misconfigured gateways that might inadvertently make these RFC services reachable from outside your protected business perimeter.

What are the first steps to address this issue?

Start by identifying all SAP NetWeaver and ABAP Platform instances across your environment to see which are running the affected SAP Kernel versions. Once located, verify the network accessibility and business importance of those systems. Engage your SAP Basis and infrastructure teams immediately to confirm ownership and coordinate a maintenance window for applying the necessary security patches provided by the vendor.

References

me.sap.com/notes/3717897

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.