CVE-2026-83187: Oracle E-Business Suite Auth Bypass

CVE-2026-83187 Overview

CVE-2026-83187 is an access control weakness [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 grants unauthorized create, delete, or modify access to critical data within Oracle Common Applications Calendar. The attacker also gains unauthorized read access to a subset of data managed by the component. Oracle disclosed the issue in the Oracle Security Alert of September 2026.

Critical Impact
An authenticated attacker can tamper with all Oracle Common Applications Calendar accessible data over the network, undermining integrity of business scheduling and workflow data.

Affected Products

Oracle E-Business Suite — Oracle Common Applications Calendar 12.2.3
Oracle E-Business Suite — Oracle Common Applications Calendar versions 12.2.4 through 12.2.14
Oracle E-Business Suite — Oracle Common Applications Calendar 12.2.15

Discovery Timeline

2026-09-15 - CVE-2026-83187 published to the National Vulnerability Database (NVD)
2026-09-17 - Last updated in NVD database
September 2026 - Oracle addressed the issue in the Oracle Security Alert September 2026

Technical Details for CVE-2026-83187

Vulnerability Analysis

The vulnerability resides in the Applications Calendar component of the Oracle Common Applications Calendar module within Oracle E-Business Suite. It is categorized under [CWE-284] Improper Access Control, indicating that the component does not correctly enforce restrictions on actions available to authenticated users. An attacker holding any low-privilege account within the E-Business Suite tenant can send crafted HTTP requests to the Calendar interface to perform unauthorized actions. The attack requires no user interaction and no elevated permissions. Oracle rates the confidentiality impact as low and the integrity impact as high, reflecting broad tampering potential without full data readout.

Root Cause

The root cause is missing or insufficient authorization checks on Calendar operations exposed over HTTP. Server-side handlers appear to trust the presence of a valid session without validating whether the session principal owns or is entitled to modify the target resource. As a result, low-privilege accounts inherit write access to Calendar records intended for other users or administrative scope.

Attack Vector

Exploitation occurs remotely over the network via standard HTTP requests to the E-Business Suite front end. The attacker authenticates with any low-privilege user, then issues Calendar API or servlet requests that create, modify, or delete entries outside the account's authorized scope. Because attack complexity is low and no user interaction is required, exploitation can be automated against exposed Oracle E-Business Suite deployments.

No public proof-of-concept exploit was available at time of publication. Refer to the Oracle Security Alert September 2026 for vendor technical details.

Detection Methods for CVE-2026-83187

Indicators of Compromise

Unexpected creation, deletion, or modification of Calendar entries owned by users other than the acting session principal.
HTTP requests to Oracle Common Applications Calendar endpoints originating from accounts that historically never invoked Calendar write operations.
Anomalous spikes in Calendar-related POST, PUT, or DELETE traffic from a single low-privilege session.

Detection Strategies

Enable Oracle E-Business Suite Sign-On Audit and Page Access Tracking to log Calendar module invocations by user and responsibility.
Correlate authentication logs with Calendar object change events to identify write actions performed outside expected user scope.
Baseline normal Calendar activity per responsibility, then alert on deviation such as cross-user record modification.

Monitoring Recommendations

Forward Oracle E-Business Suite application and access logs into a central SIEM for continuous analysis and retention.
Monitor the front-end web tier (Oracle HTTP Server) for HTTP request patterns targeting OA.jsp and Calendar-related servlets from low-privilege accounts.
Review database audit trails for FND_CALENDAR and related Calendar schema tables to detect unauthorized DML activity.

How to Mitigate CVE-2026-83187

Immediate Actions Required

Apply the security fix referenced in the Oracle Security Alert of September 2026 to all Oracle E-Business Suite instances running versions 12.2.3 through 12.2.15.
Inventory internal and internet-facing E-Business Suite deployments and prioritize patching those exposed to broader user populations.
Review recent Calendar activity for signs of unauthorized modification prior to patch deployment.

Patch Information

Oracle released fixes as part of the September 2026 Security Alert cycle. Administrators should follow the guidance in the Oracle Security Alert September 2026 advisory to obtain and apply the appropriate patch for Oracle E-Business Suite 12.2. Validate application in a non-production environment before rolling out to production.

Workarounds

Restrict network access to the Oracle E-Business Suite front end using firewall, reverse-proxy, or VPN controls to limit exposure to trusted users only.
Temporarily reduce or remove Calendar responsibilities from low-privilege user accounts that do not require Calendar functionality.
Increase audit granularity on Calendar-related tables and endpoints until the vendor patch is deployed.

bash

# Example: audit Calendar write activity via database session-level auditing
sqlplus / as sysdba
AUDIT INSERT, UPDATE, DELETE ON APPLSYS.FND_CALENDAR BY ACCESS;