CVE-2026-91658 in Essbase
Summary
by MITRE • 10/22/2026
Vulnerability in Oracle Essbase (component: Security). The supported version that is affected is 21.8.3.0.0. Easily exploitable vulnerability allows low privileged attacker with network access via HTTP to compromise Oracle Essbase. While the vulnerability is in Oracle Essbase, attacks may significantly impact additional products (scope change). Successful attacks of this vulnerability can result in takeover of Oracle Essbase. CVSS 3.1 Base Score 9.9 (Confidentiality, Integrity and Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H).
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Analysis
by VulDB Data Team • 10/22/2026
The identified vulnerability resides within the Security component of Oracle Essbase version 21.8.3.0.0, representing a critical security flaw that undermines the integrity and confidentiality of the application environment. This issue is classified as an easily exploitable vulnerability that permits low-privileged attackers to achieve complete system compromise. The attack vector is network-based via HTTP, meaning that no physical access or local interaction with the target machine is required for exploitation. An attacker merely needs valid credentials at a low privilege level and network connectivity to the affected service to initiate the exploit sequence. This accessibility significantly lowers the barrier to entry for malicious actors compared to vulnerabilities requiring high privileges or complex user interactions.
The technical nature of this flaw allows an authenticated but unprivileged user to escalate their access rights effectively leading to full administrative control over Oracle Essbase. The impact is severe, as indicated by a CVSS 3.1 Base Score of 9.9 out of 10. This high score reflects critical impacts across all three pillars of the CIA triad: Confidentiality, Integrity, and Availability. A successful exploitation results in total takeover of the Oracle Essbase instance, allowing attackers to read sensitive data, modify configurations or datasets without authorization, and disrupt service availability by crashing processes or locking out legitimate users. The presence of a scope change indicates that while the vulnerability is technically located within Essbase, its consequences can ripple outward to impact additional products integrated with or dependent on this component, thereby expanding the blast radius beyond the immediate application boundary.
From an industry standard perspective, this vulnerability aligns closely with CWE-269 Improper Privilege Management and CWE-780 Use of RSA Key in a Random Number Generator if related to cryptographic weaknesses, though more broadly it represents a classic case of privilege escalation due to insufficient access control checks. In terms of the MITRE ATT&CK framework, this vulnerability facilitates Initial Access through valid accounts followed by Lateral Movement or Privilege Escalation techniques such as T1078 Valid Accounts and potentially T1068 Exploitation for Privilege Escalation depending on the specific mechanism used to gain higher privileges. The network-based nature of the attack corresponds to remote exploitation vectors often seen in web application vulnerabilities where input validation or session management is flawed.
The operational impact of this vulnerability extends beyond simple data theft. With full control over Oracle Essbase, an attacker can manipulate multidimensional analytical models, alter business intelligence reports, and potentially inject malicious logic into calculation scripts that execute on the server side. This compromises the reliability of decision-making processes for organizations relying on accurate analytics. Furthermore, because the scope changes to impact additional products, attackers may use this foothold as a pivot point to attack other systems in the enterprise network that trust or interact with Essbase data stores or APIs. This creates a significant risk of widespread organizational disruption and potential regulatory non-compliance due to unauthorized access to protected information assets.
Mitigation strategies must prioritize immediate patching if an official update is available from Oracle for version 21.8.3.0.0. In the interim, organizations should enforce strict network segmentation to limit HTTP access to Essbase services only from trusted subnets and authorized IP ranges. Implementing robust Web Application Firewalls can help detect and block exploit attempts by filtering malicious payloads before they reach the application layer. Additionally, enforcing multi-factor authentication for all administrative accounts and applying the principle of least privilege ensures that even if an attacker gains initial access with low privileges, their ability to escalate further is restricted. Regular auditing of user permissions and monitoring for anomalous activity patterns can also aid in early detection of exploitation attempts before significant damage occurs.