CVE-2026-11340: Liman MYS Authorization Bypass Flaw

CVE-2026-11340 Overview

CVE-2026-11340 is a Missing Authorization vulnerability [CWE-862] affecting HAVELSAN Inc. Liman MYS. The flaw allows authenticated attackers to access functionality that is not properly constrained by Access Control Lists (ACLs). Liman MYS releases prior to Master.1107 are affected.

The issue is exploitable over the network with low attack complexity and requires only low-privileged authentication. Successful exploitation can compromise integrity and availability while exposing limited confidential data.

Critical Impact
Low-privileged users can invoke restricted functionality in Liman MYS, enabling unauthorized modification of system state and disruption of managed services.

Affected Products

HAVELSAN Inc. Liman MYS versions before Master.1107

Discovery Timeline

2026-07-07 - CVE-2026-11340 published to NVD
2026-07-07 - Last updated in NVD database

Technical Details for CVE-2026-11340

Vulnerability Analysis

CVE-2026-11340 stems from missing authorization checks within Liman MYS, a management platform developed by HAVELSAN Inc. The application exposes functionality that should be restricted to specific roles but fails to enforce ACLs at the request-handling layer. Any authenticated user can therefore invoke endpoints or operations intended for higher-privileged roles.

The vulnerability class is Missing Authorization [CWE-862]. Applications affected by this weakness typically perform authentication correctly but omit or misapply role-based checks before executing sensitive server-side logic. This leaves privileged operations reachable through direct requests.

Exploitation impacts integrity and availability at a high level while exposing limited confidentiality. Attackers can alter managed configurations, execute administrative workflows, or disrupt services provided by Liman MYS.

Root Cause

The underlying defect is the absence of enforced authorization checks on privileged application functionality. Session or token validation occurs, but role and permission validation is missing on affected code paths. Without these checks, ACL policies defined for the platform are not honored at runtime.

Attack Vector

An attacker with valid low-privileged credentials sends crafted HTTP requests to functionality that should be restricted by ACL. Because authorization is not enforced, the server processes the request and executes the privileged action. No user interaction is required, and the attack is executable across the network.

See the Siber Güvenlik Notification TR-26-0504 for the vendor-coordinated disclosure.

Detection Methods for CVE-2026-11340

Indicators of Compromise

Requests from low-privileged accounts to administrative endpoints within Liman MYS
Unexpected configuration changes, user modifications, or service restarts triggered by non-admin sessions
HTTP 200 responses on privileged routes for accounts that lack administrative role assignments

Detection Strategies

Correlate authenticated session identifiers with the role attributes attached to sensitive API calls to identify authorization mismatches
Baseline normal usage per role in Liman MYS and alert on deviations where non-admin users access admin-only functions
Review application audit logs for privileged actions attributed to accounts that should not possess those permissions

Monitoring Recommendations

Forward Liman MYS application and web server logs to a centralized log platform for retention and correlation
Enable alerts for repeated requests to administrative routes from a single low-privileged account
Monitor for anomalous configuration change frequency and out-of-hours administrative activity

How to Mitigate CVE-2026-11340

Immediate Actions Required

Upgrade Liman MYS to release Master.1107 or later as published by HAVELSAN Inc.
Audit existing user accounts and remove unnecessary privileges to reduce the population of accounts able to exploit the flaw
Rotate credentials for accounts that may have been exposed prior to patching

Patch Information

HAVELSAN Inc. addresses CVE-2026-11340 in Liman MYS release Master.1107. Administrators should apply this release through the standard vendor update process. Refer to the Siber Güvenlik Notification TR-26-0504 for the official advisory.

Workarounds

Restrict network access to Liman MYS management interfaces using firewall rules or VPN gating until the patch is applied
Disable or suspend low-privileged accounts that do not require active access during the remediation window
Increase logging verbosity on Liman MYS to capture all authenticated API activity for post-incident review

bash

# Example: restrict access to Liman MYS management interface with iptables
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP