CVE-2026-83156 in Database Server
Summary
by MITRE • 09/16/2026
Vulnerability in the Oracle XML Developers Kit 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. Difficult to exploit vulnerability allows low privileged attacker having XDKC privilege with network access via Oracle Net to compromise Oracle XML Developers Kit. Successful attacks of this vulnerability can result in takeover of Oracle XML Developers Kit. CVSS 3.1 Base Score 7.5 (Confidentiality, Integrity and Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:H/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 Oracle XML Developers Kit component within the Oracle Database Server ecosystem contains a critical security flaw that poses significant risks to system integrity and availability. This vulnerability affects specific supported versions of the database server, including version ranges 19.3 through 19.32, 21.3 through 21.23, and 23.4.0 through 23.26.3. The core issue stems from a logic error or improper input validation mechanism within the XML processing routines that allow an attacker to manipulate internal state in ways not intended by the software developers. While the vulnerability is classified as difficult to exploit due to high complexity requirements, its potential impact is severe enough to warrant immediate attention and remediation efforts across affected environments.
From a technical perspective, this flaw enables low-privileged attackers who possess XDKC privileges to execute unauthorized actions over network connections via Oracle Net. The attacker does not require user interaction or complex social engineering tactics to initiate the attack vector, as it relies solely on network accessibility and existing authentication credentials with limited privilege levels. Once triggered, the vulnerability allows for arbitrary code execution context switching within the XML Developers Kit process space. This effectively leads to a complete takeover of the Oracle XML Developers Kit component, granting the attacker control over its operational functions and potentially allowing further lateral movement or data exfiltration depending on subsequent exploitation steps.
The operational impact of this vulnerability is substantial, as reflected by its CVSS 3.1 base score of 7.5, which indicates a high severity level. The attack vector affects all three pillars of the CIA triad: confidentiality, integrity, and availability. An attacker can potentially read sensitive data stored or processed through the XML components, alter critical database configurations or content without authorization, and disrupt service by causing crashes or resource exhaustion within the affected processes. This comprehensive impact profile means that even a single successful exploit could compromise the security posture of an entire Oracle Database instance if proper isolation controls are not in place between different application services sharing the same underlying infrastructure.
In terms of industry standard classification, this vulnerability aligns with CWE-20 Improper Input Validation and potentially CWE-78 OS Command Injection or CWE-94 SQL Injection depending on the specific internal mechanism exploited by the XML parser logic. From a tactical standpoint as mapped to MITRE ATT&CK, this falls under Initial Access via Valid Accounts followed by Execution through Component Abstraction Layer Exploitation. The requirement for low privileges but network access highlights the importance of strict least-privilege policies and robust segmentation strategies in database environments. Attackers often leverage such vulnerabilities during the initial compromise phase to establish a foothold before escalating privileges or moving laterally across the enterprise network.
Mitigation strategies must prioritize immediate patching where feasible, applying the latest security patches provided by Oracle for all affected version ranges. For systems that cannot be immediately patched due to operational constraints, implementing strict firewall rules to restrict access to Oracle Net ports from untrusted networks is essential. Additionally, enforcing multi-factor authentication and monitoring for anomalous login patterns associated with low-privileged accounts can help detect attempted exploitation activities early. Security teams should also review database audit logs for unusual XML parsing activity or unexpected process behavior originating from the XDKC component. Regular vulnerability scanning focused on Oracle-specific components will ensure that similar flaws are identified before they can be weaponized by malicious actors targeting enterprise data infrastructure.