CVE-2026-21931 is a vulnerability identified in Oracle APEX Sample Applications, specifically in the Brookstrut Sample App component, affecting versions 23.2.0, 23.2.1, 24.1.0, 24.2.0, and 24.2.1. The flaw allows a low privileged attacker with network access via HTTP to compromise these sample applications by exploiting a weakness that requires user interaction from a third party. The vulnerability enables unauthorized update, insert, or delete operations, as well as unauthorized read access to subsets of data accessible through the Oracle APEX Sample Applications. The attack vector involves network access with low attack complexity and requires the attacker to have some privileges (PR:L) and user interaction (UI:R), but no elevated privileges or direct authentication bypass. The scope is changed (S:C), meaning the vulnerability can affect resources beyond the initially vulnerable component, potentially impacting other Oracle products integrated or dependent on these sample applications. The CVSS score of 5.4 reflects limited confidentiality and integrity impacts, with no availability impact. Although no known exploits are currently reported, the vulnerability's ease of exploitation and potential to affect multiple products make it a significant concern for organizations relying on Oracle APEX environments.

For European organizations, this vulnerability poses a risk of unauthorized data manipulation and disclosure within Oracle APEX environments, which are widely used for rapid web application development and deployment. The ability for a low privileged attacker to perform unauthorized insert, update, delete, and read operations could lead to data integrity issues, leakage of sensitive information, and potential compliance violations under regulations such as GDPR. The requirement for user interaction means phishing or social engineering could be leveraged to trigger exploitation, increasing the risk in environments with less stringent user awareness training. Additionally, the scope change indicates that exploitation could affect other Oracle products interconnected with APEX, potentially broadening the impact. Organizations in sectors such as finance, healthcare, and government, which often use Oracle technologies and handle sensitive data, may face increased operational and reputational risks if this vulnerability is exploited.

European organizations should immediately assess their Oracle APEX environments to identify deployments of the affected sample application versions (23.2.0 through 24.2.1). Where possible, upgrade to patched versions once Oracle releases fixes or apply any available interim mitigations such as disabling or restricting access to the vulnerable sample applications. Implement strict network segmentation and firewall rules to limit HTTP access to Oracle APEX environments only to trusted users and networks. Enhance user awareness training to reduce the risk of social engineering attacks that could trigger the required user interaction. Monitor Oracle APEX logs for unusual insert, update, or delete activities and unauthorized data access attempts. Employ Web Application Firewalls (WAF) with custom rules to detect and block suspicious HTTP requests targeting APEX sample applications. Finally, review and tighten application-level access controls to minimize privileges assigned to users and services interacting with Oracle APEX.