CVE-2026-83271 in Database Server
Summary
by MITRE • 09/16/2026
Vulnerability in the RDBMS component of Oracle Database Server. Supported versions that are affected are 19.3-19.32, 21.3-21.23 and 23.4.0-23.26.3. Easily exploitable vulnerability allows low privileged attacker having Execute on DBMS_REDEFINITION 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 • 09/16/2026
The identified vulnerability resides within the Relational Database Management System component of Oracle Database Server, specifically affecting supported versions including releases 19.3 through 19.32, 21.3 through 21.23, and 23.4.0 through 23.26.3. This flaw represents a critical security deficiency that allows for the compromise of the database server's integrity and availability under specific conditions. The vulnerability is characterized by its ease of exploitation, which significantly lowers the barrier for potential attackers to execute malicious actions against the target system. It is classified as an easily exploitable vulnerability due to the low complexity required to trigger the underlying technical flaw within the RDBMS engine.
The operational context for this exploit involves a low-privileged attacker who possesses Execute privileges on the DBMS_REDEFINITION package and has network access via Oracle Net. The presence of these specific prerequisites indicates that the attack vector is remote but requires initial foothold or credential theft to gain even minimal database permissions. Once an attacker achieves this level of access, they can leverage the vulnerability in the RDBMS component to escalate privileges beyond their current standing. This escalation path leads directly to a complete takeover of the RDBMS instance, granting the attacker unrestricted control over the underlying system resources and data stored within the database environment.
The impact of a successful exploitation is severe, encompassing full compromise of confidentiality, integrity, and availability as reflected in the CVSS 3.1 Base Score of 8.8. The high score indicates that an attacker can exfiltrate sensitive data, alter critical records without authorization, or disrupt service operations entirely by taking over the RDBMS process. This level of impact aligns with CWE-269 Improper Privilege Management and CWE-740 Privilege Assignment to Wrong Entity, as the vulnerability allows a user with limited rights to perform actions reserved for higher privileged accounts. Furthermore, from an ATT&CK perspective, this scenario maps to techniques involving privilege escalation such as T1078 Valid Accounts or T1548 Abuse Elevation Control Mechanism, depending on the specific mechanism used within DBMS_REDEFINITION to bypass security controls.
Mitigation strategies must focus on immediate patching and strict access control enforcement. Organizations running affected versions should apply the latest Oracle Critical Patch Update (CPU) releases that address this specific RDBMS flaw. In addition to software updates, it is imperative to review and restrict permissions associated with DBMS_REDEFINITION across all database instances. This package allows for online table redefinition operations which can be abused if not properly secured; therefore, execute privileges should be granted only to trusted administrative accounts that require such functionality. Network segmentation policies should also be reviewed to ensure that Oracle Net access is restricted to authorized hosts and users, thereby reducing the attack surface available to potential low-privileged attackers attempting to exploit this vulnerability remotely.