CVE-2026-91636 in Essbase
Summary
by MITRE • 10/21/2026
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 unauthorized access to critical data or complete access to all Oracle Essbase accessible data. CVSS 3.1 Base Score 7.7 (Confidentiality impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N).
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Analysis
by VulDB Data Team • 10/21/2026
The identified vulnerability resides within the security component of Oracle Essbase, specifically affecting version 21.8.3.0.0 and potentially other supported releases depending on configuration. This flaw represents a critical weakness in how the application handles authentication and authorization checks for HTTP-based requests. The core technical issue involves an insufficient validation mechanism that allows low-privileged users to bypass intended access controls when interacting with the system over network protocols. By exploiting this logic error, an attacker who possesses valid but limited credentials can manipulate request parameters or session states to escalate their privileges beyond what was originally granted by the system administrator. This type of flaw is typically categorized under CWE-269 Improper Privilege Management or CWE-862 Missing Authorization, as it fundamentally breaks the principle that users should only have access to resources and functions appropriate for their assigned role.
The operational impact of this vulnerability is severe due to its network accessibility and low barrier to exploitation. Because the attack vector requires only a low privileged account and standard HTTP connectivity, an attacker does not need complex setup or physical proximity to initiate the exploit. Once successful, the immediate consequence is unauthorized access to critical data stored within the Essbase environment. Given that Oracle Essbase often serves as a central repository for enterprise planning, budgeting, and forecasting data, this breach can lead to significant confidentiality losses. The CVSS 3.1 base score of 7.7 reflects high impact on confidentiality with no direct impact on integrity or availability in the baseline assessment. However, the scope change noted indicates that compromising Essbase may allow lateral movement into other integrated Oracle products, thereby expanding the blast radius beyond a single application to potentially affect entire enterprise data ecosystems.
From an offensive security perspective, this vulnerability aligns closely with MITRE ATT&CK techniques related to Credential Access and Privilege Escalation on Local Systems or within Application Layers. An attacker would likely leverage existing valid credentials obtained through phishing or credential stuffing attacks to gain initial foothold as a low-privileged user. Subsequently, they would exploit the specific HTTP request manipulation associated with this flaw to escalate privileges. This pathway enables the exfiltration of sensitive financial models, strategic plans, and proprietary business intelligence data without triggering standard high-level security alerts that might monitor for brute-force or injection attacks from unauthenticated sources. The ability to access all Oracle Essbase accessible data means that once inside, an attacker can view, copy, or potentially modify underlying cubes and dimensions if further integrity flaws exist, though the primary reported impact is confidentiality loss.
Mitigation strategies must focus on both immediate remediation and long-term architectural hardening. The most effective countermeasure is to apply the latest security patches provided by Oracle for version 21.8.3.0.0 immediately upon availability or through interim workarounds if a patch is not yet released. Organizations should also enforce strict network segmentation to limit HTTP access to Essbase servers, ensuring that only authorized application tiers and management consoles can communicate with the service. Implementing multi-factor authentication for all user accounts adds an additional layer of defense against credential theft, which is often the precursor to this type of exploitation. Furthermore, deploying Web Application Firewalls configured to detect anomalous privilege escalation patterns or unusual HTTP request structures can help identify and block attempts to exploit this specific logic flaw before it succeeds. Regular audits of user permissions should be conducted to ensure that low-privileged accounts do not possess unnecessary access rights that could be leveraged in such attacks.