CVE-2026-91616 in Middleware Common Libraries and Tools
Summary
by MITRE • 10/22/2026
Vulnerability in the Oracle Middleware Common Libraries and Tools product of Oracle Fusion Middleware (component: Remote Diagnostic Agent). Supported versions that are affected are 12.2.1.4.0 and 14.1.1.0.0. Difficult to exploit vulnerability allows unauthenticated attacker with network access via HTTP to compromise Oracle Middleware Common Libraries and Tools. Successful attacks of this vulnerability can result in unauthorized read access to a subset of Oracle Middleware Common Libraries and Tools accessible data. CVSS 3.1 Base Score 3.7 (Confidentiality impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N).
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Analysis
by VulDB Data Team • 10/22/2026
The identified vulnerability resides within the Remote Diagnostic Agent component of Oracle Middleware Common Libraries and Tools, a critical subsystem in Oracle Fusion Middleware versions 12.2.1.4.0 and 14.1.1.0. This flaw represents an information disclosure weakness that allows unauthenticated attackers to access sensitive data without prior authentication credentials. The vulnerability is characterized by its network-based attack vector, requiring only HTTP connectivity to the target system, which significantly expands the potential attack surface in environments where these middleware components are exposed to internal or external networks. Despite being classified as difficult to exploit due to high complexity requirements for successful exploitation, the lack of required authentication makes it a persistent risk for organizations that have not implemented strict network segmentation or access controls around their diagnostic interfaces.
From a technical perspective, this vulnerability aligns with CWE-200, which defines Information Exposure, and specifically relates to improper restriction of information accessible to an unauthenticated actor. The Remote Diagnostic Agent is designed to collect system metrics and logs for troubleshooting purposes, but in its vulnerable state, it fails to enforce adequate access controls on certain endpoints or data retrieval mechanisms. This oversight permits a remote attacker who can reach the service via HTTP to query diagnostic interfaces that should be restricted to authorized administrators only. The complexity of exploitation suggests that specific conditions or sequences may be required to trigger the flaw, such as precise timing or particular request structures, which mitigates immediate widespread automated attacks but does not eliminate the risk for targeted adversaries with sufficient technical expertise.
The operational impact of this vulnerability is primarily centered on confidentiality breaches rather than integrity or availability disruptions. Successful exploitation results in unauthorized read access to a subset of data managed by Oracle Middleware Common Libraries and Tools. This could include sensitive configuration details, internal system states, user session information, or other proprietary data that aids further reconnaissance efforts against the organization's infrastructure. While the CVSS 3.1 base score is low at 3.7 due to limited impact on confidentiality (C:L) and no impact on integrity or availability, this does not diminish the strategic value of such leaks in a broader attack chain. Attackers often use initial information disclosure as a stepping stone for privilege escalation, lateral movement, or crafting more sophisticated social engineering attacks based on revealed organizational structures.
In terms of threat modeling, this vulnerability maps to MITRE ATT&CK technique T1087, specifically Account Discovery and potentially T1539 if it involves stealing credentials directly from memory or configuration files. The attack vector is classified as Network (AV:N) with High complexity (AC:H) and No privileges required (PR:N), indicating that while the barrier to entry is moderate due to exploitation difficulty, the lack of authentication requirement makes it a significant concern for any externally facing middleware deployment. Organizations must recognize that even low-severity vulnerabilities can contribute to systemic risk when combined with other weaknesses or misconfigurations within the network architecture.
Mitigation strategies should focus on both immediate remediation and long-term architectural improvements. Oracle has likely released patches addressing this specific flaw in subsequent updates of Fusion Middleware, so applying the latest security bundles is the primary corrective action. For environments where patching is not immediately feasible, implementing strict firewall rules to restrict access to the Remote Diagnostic Agent ports solely from trusted administrative IP addresses can effectively neutralize the risk by preventing unauthenticated network access. Additionally, enabling HTTPS with mutual TLS authentication for diagnostic interfaces ensures that even if a vulnerability exists in HTTP handling, it cannot be exploited without valid client certificates and server verification. Regular auditing of middleware configurations against industry standards such as CIS Benchmarks will help identify similar misconfigurations across other components, ensuring a more resilient security posture overall.