Impact

Successful exploitation of CVE-2026-13696 could allow an unauthenticated attacker to bypass authentication mechanisms, gain unauthorized access to the Liman MYS system, and potentially the underlying LDAP directory. This could lead to information disclosure, unauthorized modification of user accounts, groups, and permissions, or even full administrative compromise of the directory service. The highly sensitive nature of LDAP directories means that compromise could have widespread effects on user management, access control across multiple integrated systems, and lead to significant data breaches or operational disruption.

Recommendation

• Patch CVE-2026-13696 on all HAVELSAN Inc. Liman MYS instances immediately by upgrading to release.Master.1107 or later.

Attack Chain

1. Attacker Crafts Malicious Data: An unauthenticated attacker creates data intended to be malicious (e.g., altered configuration, spoofed commands, or falsified reports).
2. Attacker Forges Cryptographic Signature: The attacker generates a cryptographic signature for the malicious data that appears legitimate but is actually forged.
3. Attacker Submits Crafted Payload: The attacker sends the malicious data bundle, including the forged signature, to a vulnerable HAVELSAN Liman MYS instance.
4. Liman MYS Processes Incoming Data: The application receives the data and attempts to validate its authenticity by verifying the accompanying cryptographic signature.
5. Signature Verification Bypass (CVE-2026-11348): Due to the inherent flaw in the signature verification logic (CWE-347), Liman MYS fails to correctly identify the forged signature as invalid.
6. Data Accepted as Legitimate: The Liman MYS application mistakenly authenticates and accepts the malicious data as originating from a trusted or authorized source.
7. Application Processes Faked Data: The application proceeds to process the attacker-controlled data, believing it to be genuine and reliable.
8. Impact Realized: The faked data is then integrated into the system, leading to consequences such as data integrity compromise, execution of unauthorized commands, or other logical abuses depending on the attacker's specific objective.

Impact

This vulnerability allows an attacker to "fake the source of data," meaning they can potentially inject arbitrary malicious information into the Liman MYS system, bypass integrity checks, or spoof legitimate entities. The CVSS v3.1 base score of 8.1 (High) indicates significant potential for impact, including high confidentiality, integrity, and availability impacts, if successfully exploited. Organizations using affected versions of HAVELSAN Liman MYS could face data corruption, unauthorized system behavior, or loss of trust in the data managed by the platform. Without immediate patching, affected systems remain vulnerable to external manipulation, potentially impacting operational reliability and security.

Recommendation

• Patch CVE-2026-11348 immediately by updating HAVELSAN Liman MYS to release.Master.1107 or a newer version as advised by the vendor.
• Review the vendor advisory at https://siberguvenlik.gov.tr/guvenlik-bildirimleri/detay/tr-26-0504 for further guidance and details on the patch.

Attack Chain

1. An attacker, possessing valid low-privileged credentials, identifies a vulnerable HAVELSAN Liman MYS instance (versions prior to release.Master.1107).
2. The attacker authenticates to the Liman MYS web interface using their legitimate low-privileged account.
3. The attacker then crafts a request or navigates to a specific sensitive function or resource that should typically be restricted by ACLs to higher-privileged users.
4. Due to the missing authorization vulnerability (CVE-2026-11340), the Liman MYS application fails to adequately verify the attacker's authorization level for the requested resource or action.
5. The application incorrectly grants the low-privileged attacker access to the restricted functionality or data, bypassing intended security controls.
6. The attacker can then perform unauthorized actions, such as modifying critical system configurations, accessing sensitive information, or triggering disruptive operations.
7. This unauthorized access ultimately leads to high impact on the system's integrity (e.g., data tampering, unauthorized changes) and availability (e.g., service disruption), with a low impact on confidentiality.

Impact

The exploitation of CVE-2026-11340 can lead to severe consequences for organizations utilizing HAVELSAN Inc. Liman MYS. While specific victim counts are not available, successful exploitation by a low-privileged attacker could result in high impact to the integrity of the system and data, allowing for unauthorized modifications or deletions. Additionally, the availability of critical services could be severely affected, potentially leading to denial of service conditions. Confidentiality is also impacted, albeit at a lower level, as unauthorized data access might occur. Given Liman MYS's role, such compromise could disrupt operational management and expose sensitive internal configurations.

Recommendation

• Immediately apply the patch to update HAVELSAN Liman MYS to release.Master.1107 or a later secure version to remediate CVE-2026-11340.
• Enable comprehensive web application logging on your HAVELSAN Liman MYS instances to capture all HTTP requests, including request methods, URIs, user agents, and source IP addresses, to aid in detecting abnormal access patterns.
• Regularly audit Access Control Lists (ACLs) and authorization configurations within Liman MYS to ensure they align with the principle of least privilege and prevent similar authorization bypasses.