CVE-2026-21939 is a vulnerability identified in the SQLcl component of Oracle Database Server versions 23.4.0 through 23.26.0. SQLcl is a command-line interface used to interact with Oracle databases. The vulnerability allows an unauthenticated attacker who already has logon access to the infrastructure hosting SQLcl to compromise the SQLcl process. The attack vector is local (AV:L), requiring the attacker to have access to the system where SQLcl executes. The attack complexity is high (AC:H), meaning exploitation is not straightforward and requires specific conditions. No privileges are required (PR:N), but user interaction (UI:R) from a third party is necessary, indicating social engineering or tricking another user into performing an action is part of the exploitation chain. The vulnerability impacts confidentiality, integrity, and availability (all high), potentially allowing full takeover of SQLcl, which could lead to unauthorized data access, data manipulation, or denial of service. Although no known exploits are reported in the wild, the severity and potential impact warrant proactive mitigation. The vulnerability was published on January 20, 2026, and no patches or exploit code are currently linked, suggesting organizations should monitor Oracle advisories closely for updates.

For European organizations, this vulnerability poses a significant risk especially to those relying heavily on Oracle Database Server environments for critical business operations, including financial institutions, government agencies, and large enterprises. A successful compromise of SQLcl could lead to unauthorized data disclosure, data corruption, or service disruption, affecting business continuity and regulatory compliance (e.g., GDPR). The requirement for local access and human interaction limits the attack surface but does not eliminate risk, particularly in environments with insufficient access controls or where social engineering is feasible. The high impact on confidentiality, integrity, and availability could result in severe operational and reputational damage. Organizations with remote or hybrid work environments may face increased risk if infrastructure access controls are weak. The absence of known exploits reduces immediate threat but should not lead to complacency.

1. Restrict access to systems running SQLcl to trusted administrators only, enforcing strict network segmentation and access controls. 2. Implement robust multi-factor authentication and session monitoring for infrastructure access to reduce risk of unauthorized logon. 3. Educate users and administrators about social engineering risks to minimize chances of required human interaction exploitation. 4. Monitor Oracle security advisories closely and apply patches or updates promptly once available. 5. Use application whitelisting and endpoint protection to detect and prevent unauthorized execution of SQLcl or related processes. 6. Audit and log all SQLcl usage and infrastructure access to detect suspicious activities early. 7. Consider disabling or limiting SQLcl usage where not essential, or running it in isolated environments. 8. Employ network-level controls such as firewalls and intrusion detection systems to detect anomalous behavior related to SQLcl exploitation attempts.