CVE-2026-83186: Oracle E-Business Suite Auth Bypass Flaw

CVE-2026-83186 Overview

CVE-2026-83186 is an improper access control vulnerability [CWE-284] in the Oracle Common Applications Calendar component of Oracle E-Business Suite. The flaw affects supported versions 12.2.3 through 12.2.15. A low-privileged attacker with network access over HTTP can exploit the vulnerability without user interaction. Successful exploitation allows unauthorized creation, deletion, or modification of critical Oracle Common Applications Calendar data. It also enables a partial denial of service against the affected component.

Critical Impact
Authenticated attackers over the network can modify or destroy Oracle Common Applications Calendar data and partially disrupt service availability.

Affected Products

Oracle E-Business Suite 12.2.3 through 12.2.15
Oracle Common Applications Calendar component
Deployments exposing Oracle E-Business Suite HTTP endpoints to network-reachable users

Discovery Timeline

2026-09-15 - CVE-2026-83186 published to the National Vulnerability Database (NVD)
2026-09-17 - Last updated in NVD database
2026-09-15 - Oracle publishes Security Alert CSPUSEP2026 referencing the vulnerability

Technical Details for CVE-2026-83186

Vulnerability Analysis

The vulnerability resides in the Applications Calendar component of Oracle Common Applications Calendar, part of Oracle E-Business Suite. Oracle classifies the issue as easily exploitable, requiring only low privileges and network access via HTTP. No user interaction is required to complete an attack.

The scope of impact focuses on data integrity and availability. Attackers can create, delete, or modify data accessible to the Oracle Common Applications Calendar module. Confidentiality is not affected. Availability degradation is partial, meaning attackers can disrupt but not fully halt the affected service.

The underlying weakness maps to [CWE-284: Improper Access Control]. Authorization checks in the affected component do not adequately restrict what an authenticated low-privileged user can modify.

Root Cause

According to Oracle's advisory, the vulnerability stems from improper access control within the Applications Calendar component. The application accepts write and delete operations from authenticated sessions without sufficiently validating whether the calling account holds the required permissions for the requested resource. Oracle has not publicly released code-level details.

Attack Vector

Exploitation requires an authenticated session with any low-privilege account able to reach the Oracle E-Business Suite HTTP interface. The attacker issues crafted HTTP requests to the Applications Calendar endpoints to perform unauthorized data modification or trigger the partial denial of service condition. Because the attack vector is Network and complexity is low, exposure of the Oracle E-Business Suite web tier to broad user populations materially increases risk. Verified proof-of-concept code is not publicly available at the time of publication. See the Oracle Security Alert CSPUSEP2026 for vendor-supplied technical details.

Detection Methods for CVE-2026-83186

Indicators of Compromise

Unexpected creation, modification, or deletion events in Oracle Common Applications Calendar tables and audit logs
HTTP requests to Applications Calendar endpoints originating from accounts that do not normally interact with calendar data
Unexplained partial service degradation or elevated error rates on Oracle Common Applications Calendar endpoints

Detection Strategies

Enable and review Oracle E-Business Suite auditing (FND_AUDIT) on Applications Calendar objects to capture write and delete operations
Correlate low-privilege user sessions with unusual volumes of calendar modification requests through web-tier access logs
Baseline normal Applications Calendar API usage per user role and alert on statistical outliers

Monitoring Recommendations

Forward Oracle E-Business Suite application, database, and Apache access logs to a centralized analytics platform for correlation
Monitor for HTTP requests targeting Applications Calendar URIs with anomalous method distributions such as POST, PUT, or DELETE from unexpected source accounts
Track authentication and session activity for low-privilege accounts, particularly those newly created or dormant before sudden calendar activity

How to Mitigate CVE-2026-83186

Immediate Actions Required

Apply the patches referenced in Oracle Security Alert CSPUSEP2026 to all affected Oracle E-Business Suite instances
Inventory all Oracle E-Business Suite deployments on versions 12.2.3 through 12.2.15 and prioritize internet-exposed instances
Review Oracle Common Applications Calendar audit records for evidence of prior unauthorized activity
Restrict network access to Oracle E-Business Suite HTTP endpoints to trusted networks and identities

Patch Information

Oracle addressed CVE-2026-83186 in Security Alert CSPUSEP2026. Administrators should consult the Oracle Security Alert CSPUSEP2026 for the specific patch identifiers, prerequisites, and installation instructions for each affected Oracle E-Business Suite release in the 12.2.3 through 12.2.15 range.

Workarounds

Place Oracle E-Business Suite web tiers behind a reverse proxy or web application firewall that restricts access to authenticated corporate users
Disable or restrict access to the Oracle Common Applications Calendar module for user populations that do not require it
Enforce least privilege on Oracle E-Business Suite responsibilities and remove unused low-privilege accounts pending patch deployment

bash

# Example: restrict access to Oracle E-Business Suite Applications Calendar
# endpoints at the reverse proxy until CSPUSEP2026 patches are applied.
# Consult Oracle Support Note references in CSPUSEP2026 for exact URIs.
location ~* /OA_HTML/.*Calendar {
    allow 10.0.0.0/8;      # trusted internal network
    deny  all;
}