CVE-2026-91638 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 flaw that undermines the integrity and confidentiality of the enterprise analytics platform. This specific weakness allows for unauthorized access by an attacker who possesses only low-level privileges but has network connectivity via HTTP to the affected system. The severity of this issue is underscored by its high exploitability rating, indicating that complex attack vectors or user interaction are not required for successful exploitation. Instead, a remote adversary can leverage standard web protocols to trigger the flaw, making it particularly dangerous in environments where Essbase services are exposed to internal networks or potentially external internet-facing interfaces without sufficient segmentation or access controls.
The technical nature of this vulnerability enables an attacker to achieve complete takeover of the Oracle Essbase application environment. This level of compromise implies that the attacker gains full control over the underlying operating system processes associated with the service, allowing for arbitrary code execution, modification of configuration files, and manipulation of data stores. The impact extends beyond the immediate boundaries of the Essbase instance due to a scope change characteristic where attacks on this component significantly affect additional products within the Oracle ecosystem. This lateral movement capability means that compromising Essbase can serve as a foothold for attacking adjacent systems, databases, or middleware components that share trust relationships or network paths with the vulnerable service.
From an operational perspective, the consequences of successful exploitation are severe and multifaceted. The CVSS 3.1 base score of 9.9 reflects critical impacts across all three pillars of information security: confidentiality, integrity, and availability. Confidentiality is compromised as attackers can exfiltrate sensitive business intelligence data, financial models, and user credentials stored within the Essbase cubes or associated metadata repositories. Integrity is violated through the ability to alter analytical results, modify access controls, or inject malicious logic into calculation scripts that drive critical decision-making processes. Availability suffers because an attacker may disrupt service operations by crashing the application or locking out legitimate users, thereby halting business analytics and reporting capabilities essential for organizational functions.
This vulnerability aligns with common weakness enumerations such as CWE-269, which addresses Improper Privilege Management, specifically where low-privileged actors are granted excessive permissions or can escalate privileges through flawed authentication or authorization logic. Furthermore, the attack pattern corresponds to MITRE ATT&CK techniques related to Initial Access via Network Service Exploitation and potentially Persistence if the attacker modifies system configurations to maintain access. The use of HTTP as a transport vector highlights risks associated with unencrypted communication channels, although even HTTPS implementations may be vulnerable if server-side validation logic is flawed. Organizations must recognize that relying solely on network-level security controls like firewalls is insufficient when low-privileged accounts can trigger such deep compromises within the application layer itself.
Mitigation strategies require immediate attention to patch management and architectural hardening. Oracle should apply the latest available patches or updates for Essbase version 21.8.3.0.0 that address this specific security flaw in the authentication and authorization subsystems. In addition to applying vendor-supplied fixes, administrators must enforce strict network segmentation policies to ensure that only authorized application servers and management consoles can communicate with Essbase instances over HTTP or HTTPS protocols. Implementing Web Application Firewalls configured to detect anomalous request patterns associated with privilege escalation attempts can provide an additional layer of defense. Access control lists should be reviewed to ensure the principle of least privilege is strictly enforced, minimizing the impact if a low-privileged account is compromised. Regular vulnerability scanning and penetration testing focused on web-facing components are essential to identify similar misconfigurations before they can be exploited by malicious actors seeking lateral movement within enterprise environments.