CVE-2026-91499 in Database Server
Summary
by MITRE • 10/21/2026
Vulnerability in the RDBMS component of Oracle Database Server. Supported versions that are affected are 23.4.0-23.26.3. Easily exploitable vulnerability allows low privileged attacker having DBMS_VECTOR privilege with network access via Oracle Net to compromise RDBMS. Successful attacks of this vulnerability can result in takeover of RDBMS. CVSS 3.1 Base Score 8.8 (Confidentiality, Integrity and Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
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Analysis
by VulDB Data Team • 10/21/2026
The identified vulnerability resides within the RDBMS component of Oracle Database Server, specifically affecting supported versions ranging from 23.4.0 to 23.26.3. This security flaw is classified as easily exploitable and carries a significant risk profile with a CVSS 3.1 Base Score of 8.8, indicating a High severity level. The attack vector requires an attacker to possess low privileges but specifically the DBMS_VECTOR privilege within the database environment. Furthermore, the exploitation path necessitates network access via Oracle Net, meaning the vulnerability can be triggered remotely over a network connection rather than requiring local physical or console access.
The technical nature of this flaw allows for a complete compromise of the Relational Database Management System when successfully exploited. The presence of the DBMS_VECTOR privilege suggests that the vulnerability is likely tied to functions handling vector data types, which are increasingly common in modern database applications supporting machine learning and AI workloads. An attacker leveraging this specific privilege can execute arbitrary code or manipulate internal structures within the RDBMS engine. This capability bypasses standard security controls because it operates under an authorized but potentially misconfigured administrative context that grants access to powerful system packages.
The operational impact of a successful exploitation is severe, resulting in full takeover of the RDBMS instance. According to the CVSS metrics provided, there are high impacts on Confidentiality, Integrity, and Availability. This means attackers can exfiltrate sensitive data without detection, modify or destroy critical database records, and disrupt service availability for legitimate users. The ability to take over the RDBMS effectively grants control over all databases hosted by that instance, potentially leading to broader organizational compromise if other systems are connected to this database server.
From a classification perspective, this vulnerability aligns with CWE-269 Improper Privilege Management and likely involves elements of CWE-78 OS Command Injection or CWE-119 Memory Corruption depending on the specific implementation flaw within the vector processing logic. In terms of adversary tactics, it maps to MITRE ATT&CK techniques related to Initial Access via network services and potentially Execution through database stored procedures or external scripts enabled by the compromised RDBMS privileges. The requirement for DBMS_VECTOR privilege highlights a risk associated with granting excessive permissions to specific functional modules rather than adhering strictly to least-privilege principles across all administrative accounts.
Mitigation strategies must focus on both immediate patching and long-term architectural hardening. Oracle has released patches addressing this vulnerability, so applying the latest security updates for versions 23.4.0 through 23.26.3 is the primary remediation step. Organizations should also review their privilege assignments to ensure that the DBMS_VECTOR package is not granted unnecessarily broadly across user accounts or roles. Access controls via Oracle Net should be restricted using firewall rules and network segmentation to limit exposure of database ports to only trusted IP addresses. Additionally, implementing strict input validation for any custom applications interacting with vector data types can help mitigate exploitation attempts even if patching is delayed. Regular auditing of privilege grants and monitoring for unusual activity within the DBMS_VECTOR package will further enhance security posture against this specific threat vector.