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.