Medium Severity
Affected system
Patch Day
Released on
SAP Note
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A note with CVSS 4.7 for component BC-FES-ITS was released by SAP on 09.02.2021. The correction/advisory 2973428 was described with "Reverse Tabnabbing vulnerability within SAP NetWeaver Application Server ABAP (Applications based on SAP GUI for HTML)" and affects the system type Kernal.

A workaround does not exist, according to SAP Security Advisory team. It is advisable to implement the correction as monthly patch process.

The vulnerability addressed is reverse tabnabbing within Kernal.

Reverse tabnabbing is an attack where a page linked from the target page is able to rewrite that page, for example to replace it with a phishing site. The following figure shows a brief illustration:

Reverse Tabnabbing Overview

While the user was originally on the correct page there is a high risk they will not notice that it has been changed to a phishing site.

Risk specification

SAP GUI for HTML allows an unauthenticated remote attacker to redirect users to a malicious site due to insufficient reverse tabnabbing URL validation.


The solution impacts the method 'cl_gui_html_viewer'. Therefore, to resolve the issue the most current SAPEXE SAR for your kernel needs to be installed.



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