CVE-2025-36178: IBM Controller Auth Bypass Vulnerability

CVE-2025-36178 Overview

CVE-2025-36178 affects IBM Controller versions 11.0.0 through 11.0.1 FP7 and 11.1.0 through 11.1.3 FP1. The vulnerability allows an authenticated user to bypass input validation because the application improperly validates client-side input of file size. The weakness maps to [CWE-1284] (Improper Validation of Specified Quantity in Input) and is classified as a network-exploitable issue requiring low-privilege authentication.

Critical Impact
An authenticated attacker can bypass client-side file size validation in IBM Controller, potentially affecting integrity and availability of the application through malformed or oversized uploads.

Affected Products

IBM Controller 11.0.0 through 11.0.1 FP7
IBM Controller 11.1.0 through 11.1.3 FP1
IBM Controller server components handling file upload workflows

Discovery Timeline

2026-09-18 - CVE-2025-36178 published to NVD
2026-09-18 - Last updated in NVD database

Technical Details for CVE-2025-36178

Vulnerability Analysis

CVE-2025-36178 exists because IBM Controller relies on client-side validation to enforce file size constraints. An authenticated user can bypass these checks by modifying requests before they reach the server, submitting file uploads that exceed intended limits. Because the server does not independently enforce the size restriction, the application processes data that should have been rejected during input handling.

The flaw is categorized under [CWE-1284], which describes weaknesses where an input quantity such as size, length, or count is not validated against expected bounds. In this case, the missing server-side check permits the client to dictate size parameters, undermining the trust boundary between the browser and the Controller server.

Root Cause

The root cause is improper validation of client-supplied file size data. IBM Controller trusts values that originate from the client without re-validating them at the server tier. Attackers with valid accounts can tamper with these values using intercepting proxies or crafted HTTP requests.

Attack Vector

The vulnerability is exploitable over the network by an authenticated user with low privileges. No user interaction is required beyond the attacker's own session. Exploitation targets application integrity and availability rather than confidentiality, consistent with the observed CVSS impact profile.

No verified proof-of-concept code is publicly available. Refer to the IBM Support Page for vendor guidance on affected components and remediation.

Detection Methods for CVE-2025-36178

Indicators of Compromise

HTTP upload requests to IBM Controller endpoints containing file payloads larger than documented application limits.
Application or web server logs showing successful uploads that exceed the configured client-side size threshold.
Repeated upload requests from a single authenticated session with abnormal Content-Length values.

Detection Strategies

Instrument reverse proxies or WAF rules to log and flag file uploads exceeding expected size for Controller endpoints.
Correlate authenticated user activity with upload volume and frequency to identify anomalous behavior.
Review IBM Controller audit trails for repeated validation failures or oversized transaction submissions.

Monitoring Recommendations

Enable verbose logging on the Controller application tier for file upload handlers and preserve Content-Length headers.
Forward web server access logs to a centralized SIEM for baseline analysis of upload sizes per user account.
Alert on authenticated sessions that generate a sudden increase in large or malformed upload attempts.

How to Mitigate CVE-2025-36178

Immediate Actions Required

Inventory all IBM Controller deployments and identify instances running 11.0.0 through 11.0.1 FP7 or 11.1.0 through 11.1.3 FP1.
Apply the IBM-provided fix pack referenced in the vendor advisory as soon as change windows allow.
Restrict Controller access to trusted networks and authenticated users pending patch deployment.

Patch Information

IBM has published remediation guidance on the IBM Support Page. Administrators should consult the advisory for the exact fix pack levels that resolve the improper validation logic and follow IBM's upgrade procedure for Controller.

Workarounds

Enforce server-side file size limits at an upstream reverse proxy or WAF for Controller upload endpoints.
Review and tighten role-based access controls to limit which authenticated users can perform uploads.
Monitor upload activity and quarantine accounts that generate policy violations until patching is complete.

bash

# Example nginx reverse proxy directive to enforce server-side upload size limits
# Place in the server or location block fronting IBM Controller
client_max_body_size 25M;
limit_except GET POST { deny all; }