CVE-2026-18650 Overview
CVE-2026-18650 is a missing authorization vulnerability [CWE-862] in HAVELSAN Inc. Liman MYS. The flaw affects Liman MYS versions from 2.2.3 before 2.3.1 and allows privilege escalation. An authenticated attacker with low privileges can invoke restricted functionality without proper authorization checks. Successful exploitation grants elevated privileges, leading to full compromise of confidentiality, integrity, and availability on the affected system.
Critical Impact
Authenticated low-privileged users can escalate to higher privileges due to missing authorization checks, leading to complete compromise of the Liman MYS management platform.
Affected Products
- HAVELSAN Liman MYS 2.2.3
- HAVELSAN Liman MYS versions after 2.2.3 and before 2.3.1
- Fixed in HAVELSAN Liman MYS 2.3.1
Discovery Timeline
- 2026-08-04 - CVE-2026-18650 published to the National Vulnerability Database
- 2026-08-04 - Last updated in NVD database
Technical Details for CVE-2026-18650
Vulnerability Analysis
CVE-2026-18650 is classified as a Missing Authorization weakness [CWE-862]. Liman MYS exposes functionality that does not verify whether the calling user holds the required role or permission. An authenticated user with a low-privileged account can therefore reach administrative or otherwise restricted operations directly.
The attack vector is network-based and requires only low privileges. No user interaction is needed, and complexity remains low. Once exploited, the attacker gains full control of resources managed by the platform, including configuration data, managed hosts, and audit-relevant state.
Root Cause
The root cause is the absence of server-side authorization enforcement on sensitive endpoints. The application authenticates the session but fails to check whether the authenticated principal is entitled to perform the requested action. This design gap allows any valid session to invoke privileged operations.
Attack Vector
An attacker first obtains valid low-privileged credentials to the Liman MYS interface. The attacker then sends crafted requests to endpoints that should be limited to administrators. Because authorization is not evaluated at the server, the operation executes with the effective privileges of the requested action rather than those of the caller. See the Siber Güvenlik Notification TR-26-0741 for advisory details.
No verified public proof-of-concept code is available for CVE-2026-18650 at this time. Refer to the linked advisory for technical detail from the vendor coordination.
Detection Methods for CVE-2026-18650
Indicators of Compromise
- Successful HTTP requests to administrative Liman MYS endpoints originating from accounts that were never provisioned with administrative roles.
- Unexpected creation, modification, or deletion of managed servers, users, or extensions inside Liman MYS.
- New privileged sessions or role changes not preceded by a legitimate administrator action.
Detection Strategies
- Compare application audit logs of privileged actions against the authoritative role assignments and alert on mismatches.
- Baseline typical request patterns per role and flag low-privileged accounts issuing administrative API calls.
- Track the Liman MYS version across the estate and mark any instance between 2.2.3 and 2.3.1 as exposed.
Monitoring Recommendations
- Forward Liman MYS access and audit logs to a centralized log platform for correlation with identity events.
- Alert on privilege changes, extension installations, and server additions performed outside change windows.
- Monitor authentication sources for unusual logins to Liman MYS from new IP ranges or geographies.
How to Mitigate CVE-2026-18650
Immediate Actions Required
- Upgrade Liman MYS to version 2.3.1 or later on all managed nodes.
- Rotate credentials for any Liman MYS account that existed on a vulnerable version, prioritizing service and administrator accounts.
- Review audit logs since deployment of 2.2.3 for unauthorized privileged actions and roll back unauthorized changes.
Patch Information
HAVELSAN addresses CVE-2026-18650 in Liman MYS 2.3.1. Administrators should apply the vendor-supplied update following the guidance in the Siber Güvenlik Notification TR-26-0741. Confirm the running version after upgrade and re-run authorization test cases before returning the system to normal operations.
Workarounds
- Restrict network access to the Liman MYS management interface using firewall rules or a VPN so only administrator workstations can reach it.
- Reduce the number of provisioned low-privileged accounts and disable any inactive users until the patch is applied.
- Enforce multi-factor authentication on all Liman MYS accounts to raise the cost of obtaining the low-privileged foothold required for exploitation.
# Verify the installed Liman MYS version and confirm it is 2.3.1 or later
liman --version
# Example: restrict management interface to an administrative subnet
iptables -A INPUT -p tcp --dport 443 -s 10.10.20.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
