CVE-2026-83355: Oracle Enterprise Manager Authentication Bypass

CVE-2026-83355 Overview

CVE-2026-83355 is a critical authentication vulnerability [CWE-287] in the Oracle Enterprise Manager for Fusion Middleware product, within the Metrics component. Supported versions 13.5 and 24.1 are affected. An unauthenticated attacker with network access via HTTP can exploit this flaw to compromise Oracle Enterprise Manager for Fusion Middleware. Successful exploitation results in full takeover of the affected instance, impacting confidentiality, integrity, and availability. Oracle disclosed the issue through its security alert program, and the vulnerability is easily exploitable without user interaction.

Critical Impact
Unauthenticated remote attackers can take over Oracle Enterprise Manager for Fusion Middleware over the network, gaining full control of a management platform that oversees enterprise middleware infrastructure.

Affected Products

Oracle Enterprise Manager for Fusion Middleware 13.5
Oracle Enterprise Manager for Fusion Middleware 24.1
Component: Metrics

Discovery Timeline

2026-09-15 - CVE-2026-83355 published to NVD
2026-09-16 - Last updated in NVD database
Oracle Security Alert CSPUSEP2026 published by Oracle

Technical Details for CVE-2026-83355

Vulnerability Analysis

The vulnerability resides in the Metrics component of Oracle Enterprise Manager for Fusion Middleware. It is classified as an Improper Authentication weakness [CWE-287], meaning the application fails to correctly verify the identity of a requester before serving privileged functionality. Because Enterprise Manager centrally administers Fusion Middleware deployments, a successful compromise grants an attacker control over configuration, monitoring, and operational functions of the managed environment.

Oracle rates the flaw as easily exploitable over HTTP without authentication or user interaction. This combination of exposure and impact makes the Metrics endpoint a high-value target for attackers scanning for exposed Oracle management consoles. Oracle documents the fix in the Oracle Security Alert CSPUSEP2026.

Root Cause

The root cause is improper authentication in the Metrics component. The affected code paths accept HTTP requests and process them without enforcing the identity verification required for sensitive operations. Oracle has not published low-level technical details beyond the advisory. Refer to the Oracle Security Alert for authoritative remediation guidance.

Attack Vector

An attacker reaches the vulnerable Metrics component over the network using HTTP requests. No credentials, prior access, or user interaction are needed. The attacker sends crafted requests to the Enterprise Manager instance and gains control of the Fusion Middleware management surface. Instances exposed to the internet or reachable from untrusted network segments face the highest risk.

No public proof-of-concept exploit or exploitation-in-the-wild reporting is available for CVE-2026-83355 at the time of publication. Oracle's advisory is the authoritative source for technical detail.

Detection Methods for CVE-2026-83355

Indicators of Compromise

Unauthenticated HTTP requests to Enterprise Manager Metrics endpoints from unexpected source addresses.
New or modified administrative accounts, jobs, or agents within Oracle Enterprise Manager for Fusion Middleware.
Unexpected outbound connections from the Enterprise Manager host after receiving external HTTP traffic.
Configuration changes to monitored Fusion Middleware targets that do not correlate with change-management records.

Detection Strategies

Inventory all Oracle Enterprise Manager for Fusion Middleware 13.5 and 24.1 deployments and validate patch status against Oracle Security Alert CSPUSEP2026.
Alert on HTTP requests to Metrics-related URIs originating from sources outside the approved administrative network.
Review authentication and access logs for successful privileged actions that lack a corresponding login event.

Monitoring Recommendations

Forward Enterprise Manager application, access, and audit logs to a centralized SIEM for correlation and long-term retention.
Baseline normal administrative activity on Enterprise Manager and alert on deviations such as off-hours agent deployment or job creation.
Monitor egress traffic from Enterprise Manager hosts for connections to unfamiliar destinations.

How to Mitigate CVE-2026-83355

Immediate Actions Required

Apply the fixes referenced in Oracle Security Alert CSPUSEP2026 to all affected 13.5 and 24.1 deployments.
Restrict network access to Enterprise Manager HTTP interfaces so that only trusted administrative networks can reach them.
Audit administrative accounts, agents, jobs, and configuration changes for signs of prior exploitation.
Rotate credentials and API keys used by Enterprise Manager if compromise is suspected.

Patch Information

Oracle has released patches for CVE-2026-83355 via Oracle Security Alert CSPUSEP2026. Administrators must download and apply the appropriate patch for Oracle Enterprise Manager for Fusion Middleware 13.5 and 24.1 following Oracle's documented procedures. See the Oracle Security Alert CSPUSEP2026 for full package details and prerequisites.

Workarounds

Place Enterprise Manager behind a reverse proxy or firewall that enforces source-address allow-listing for HTTP access until patches are applied.
Disable or block external exposure of the Metrics component where operationally feasible.
Enforce network segmentation so Enterprise Manager consoles are unreachable from user or internet-facing zones.

bash

# Example: restrict Enterprise Manager HTTP access to an administrative subnet using iptables
iptables -A INPUT -p tcp --dport 7803 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 7803 -j DROP