CVE-2026-21931: Oracle APEX Auth Bypass Vulnerability

CVE-2026-21931 Overview

CVE-2026-21931 is a vulnerability in the Oracle APEX Sample Applications product of Oracle APEX, specifically affecting the Brookstrut Sample App component. This easily exploitable vulnerability allows a low-privileged attacker with network access via HTTP to compromise Oracle APEX Sample Applications. The attack requires human interaction from a person other than the attacker, and while the vulnerability resides in Oracle APEX Sample Applications, successful exploitation may significantly impact additional products (scope change).

Successful attacks can result in unauthorized update, insert, or delete access to some of Oracle APEX Sample Applications accessible data, as well as unauthorized read access to a subset of Oracle APEX Sample Applications accessible data.

Critical Impact

Attackers can gain unauthorized read and write access to Oracle APEX Sample Applications data with potential scope change affecting additional products.

Affected Products

• Oracle APEX Sample Applications 23.2.0
• Oracle APEX Sample Applications 23.2.1
• Oracle APEX Sample Applications 24.1.0
• Oracle APEX Sample Applications 24.2.0
• Oracle APEX Sample Applications 24.2.1

Discovery Timeline

• January 20, 2026 - CVE-2026-21931 published to NVD
• January 20, 2026 - Last updated in NVD database

Technical Details for CVE-2026-21931

Vulnerability Analysis

This vulnerability in the Brookstrut Sample App component of Oracle APEX Sample Applications allows attackers to compromise data confidentiality and integrity. The vulnerability is network-accessible via HTTP, requires low privileges to exploit, and necessitates user interaction for successful attacks. A notable characteristic of this vulnerability is the scope change indicator, meaning that while the vulnerable component is Oracle APEX Sample Applications, successful exploitation can impact resources beyond the vulnerable component's security scope.

The attack surface is the HTTP interface, making it accessible to any authenticated user who can reach the Oracle APEX installation over the network. The low attack complexity combined with the requirement for user interaction suggests this may involve some form of web application vulnerability that tricks users into performing unintended actions.

Root Cause

The vulnerability resides in the Brookstrut Sample App component within Oracle APEX Sample Applications. While Oracle has not disclosed specific technical details about the root cause, the combination of network attack vector, low privilege requirements, and the need for user interaction suggests an input validation or improper access control issue within the sample application's web interface. The scope change characteristic indicates that exploitation can affect components beyond the immediate vulnerable application.

Attack Vector

The attack vector is network-based via HTTP, requiring the attacker to have low-level authenticated access to the Oracle APEX environment. The exploitation requires social engineering or other means to achieve user interaction from a person other than the attacker. This could involve crafted URLs, malicious form submissions, or other web-based attack techniques that leverage the victim's authenticated session or permissions.

The vulnerability allows attackers to perform unauthorized data modifications (insert, update, delete) and read operations on data accessible to Oracle APEX Sample Applications. Given the scope change, these attacks may extend beyond the immediate application boundaries to affect other integrated systems or data stores.

Detection Methods for CVE-2026-21931

Indicators of Compromise

• Unusual HTTP requests targeting the Brookstrut Sample App endpoints in Oracle APEX
• Unexpected data modifications or unauthorized record changes in Oracle APEX Sample Applications databases
• Anomalous user activity patterns indicating potential exploitation attempts against sample applications

Detection Strategies

• Monitor Oracle APEX application logs for suspicious activity targeting the Brookstrut Sample App component
• Implement web application firewall (WAF) rules to detect and block anomalous HTTP requests to Oracle APEX
• Enable detailed audit logging for data access and modifications within Oracle APEX environments
• Review authentication logs for unusual low-privileged account activity

Monitoring Recommendations

• Configure alerts for unexpected data access patterns in Oracle APEX Sample Applications
• Implement user behavior analytics to identify potential social engineering attempts leading to exploitation
• Monitor for unauthorized cross-application data access that may indicate scope change exploitation

How to Mitigate CVE-2026-21931

Immediate Actions Required

• Apply the security patches provided in the Oracle Security Alert January 2026
• If patches cannot be immediately applied, consider disabling or restricting access to the Brookstrut Sample App component
• Review and restrict network access to Oracle APEX environments to authorized users only
• Educate users about potential social engineering attempts that may be used to exploit this vulnerability

Patch Information

Oracle has addressed this vulnerability in the January 2026 Critical Patch Update (CPU). Organizations running affected versions (23.2.0, 23.2.1, 24.1.0, 24.2.0, 24.2.1) should apply the relevant patches immediately. Detailed patch information and download links are available in the Oracle Security Alert January 2026.

Workarounds

• Consider removing or disabling the Brookstrut Sample App if it is not required for production operations, as sample applications are typically intended for demonstration purposes
• Implement strict access controls to limit which users can access Oracle APEX Sample Applications
• Deploy a web application firewall (WAF) with rules to filter suspicious requests to Oracle APEX endpoints
• Segment network access to Oracle APEX installations to reduce the attack surface