CVE-2025-40669: Tcman Gim Authorization Bypass Vulnerability

CVE-2025-40669 Overview

CVE-2025-40669 is an incorrect authorization vulnerability affecting TCMAN's GIM v11, a computerized maintenance management system (CMMS). The flaw allows an authenticated but unprivileged attacker to modify permissions assigned to any application user, including their own account. Exploitation requires only a crafted POST request to the /PC/Options.aspx endpoint with the parameters Command=2&Page=-1. The weakness maps to [CWE-863] (Incorrect Authorization) and enables horizontal and vertical privilege escalation within the application.

Critical Impact
A low-privileged authenticated user can grant themselves administrative permissions, undermining the application's entire access control model and exposing all managed maintenance data and workflows.

Affected Products

TCMAN GIM v11.0
TCMAN GIM deployments exposing the /PC/Options.aspx endpoint
Any GIM v11 instance accessible to authenticated low-privileged users

Discovery Timeline

2025-06-09 - CVE-2025-40669 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-40669

Vulnerability Analysis

The vulnerability resides in the permissions management functionality of TCMAN GIM v11. The application exposes an administrative action through the /PC/Options.aspx endpoint that modifies user permission assignments. The server-side handler processes requests based on the Command and Page parameters but fails to verify whether the requesting user holds the administrative role required to alter permissions.

Any authenticated session, regardless of assigned role, can invoke the permission modification routine. The flaw is a classic missing authorization check ([CWE-863]) where authentication is validated but authorization is not enforced at the function level.

Root Cause

The root cause is the absence of a server-side authorization check on the permissions modification handler invoked through POST /PC/Options.aspx?Command=2&Page=-1. The application relies on the presence of a valid session cookie without validating that the session belongs to a user entitled to change permission mappings. Access control decisions are effectively delegated to the user interface, which is bypassable by any attacker capable of sending an HTTP request directly to the endpoint.

Attack Vector

An attacker first authenticates to GIM v11 using any valid user account, including a standard unprivileged account. The attacker then issues a POST request to /PC/Options.aspx?Command=2&Page=-1 containing the payload parameters that map users to permissions. The server processes the request without verifying the caller's role, and the target user's permission set is updated. The attacker can escalate their own account to administrator, downgrade legitimate administrators, or reassign permissions across the user base.

The vulnerability is network-reachable and requires only low privileges with no user interaction. Refer to the Incibe CERT Security Notice for the coordinated advisory covering this and related issues in GIM v11.

Detection Methods for CVE-2025-40669

Indicators of Compromise

POST requests to /PC/Options.aspx containing the query string Command=2&Page=-1 originating from non-administrative user sessions.
Unexpected changes to user role or permission assignments within GIM v11 audit logs, especially self-elevation events.
New administrative sessions initiated by accounts that historically held only standard user privileges.
Access to administrative pages or functions by user accounts immediately after a request to the Options.aspx endpoint.

Detection Strategies

Enable and review GIM v11 application audit logs for permission change events and correlate them with the acting user's baseline role.
Deploy web application firewall (WAF) rules that identify POST requests to /PC/Options.aspx?Command=2&Page=-1 and evaluate the session's assigned role before allowing the request.
Alert on any HTTP 200 response to the vulnerable endpoint where the authenticated session does not belong to a known administrator.

Monitoring Recommendations

Forward IIS or reverse-proxy access logs for the GIM application to a centralized SIEM and build a detection for the specific URI and parameter pattern.
Establish a baseline of privileged accounts and alert on any deviation from that baseline within the GIM user directory.
Monitor lateral changes to permission tables in the underlying database that back the GIM application for out-of-band modifications.

How to Mitigate CVE-2025-40669

Immediate Actions Required

Restrict network access to the GIM v11 web interface to trusted management networks or VPN users only.
Audit all GIM user accounts and permission assignments for unauthorized changes since the vulnerable version was deployed.
Reset credentials for any account showing signs of privilege tampering and force re-authentication for all users.
Contact TCMAN directly to obtain a patched build and coordinate remediation planning.

Patch Information

No vendor patch URL is listed in the NVD entry at the time of publication. Coordinated disclosure was published through Spain's Incibe CERT. Consult the Incibe CERT Security Notice and contact TCMAN for a fixed release of GIM.

Workarounds

Block or filter POST requests to /PC/Options.aspx?Command=2&Page=-1 at a reverse proxy or WAF for any session not belonging to an explicit administrator allowlist.
Segment the GIM application behind an authenticating reverse proxy that enforces role-aware access control at the network edge.
Reduce the number of active GIM user accounts and enforce least-privilege role assignment to limit the pool of accounts that can trigger the flaw.
Increase audit log retention and enable alerting on permission modification events until a vendor patch is applied.

bash

# Example NGINX rule to block the vulnerable endpoint at the edge
location = /PC/Options.aspx {
    if ($arg_Command = "2") {
        if ($arg_Page = "-1") {
            return 403;
        }
    }
    proxy_pass http://gim-backend;
}