Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
-
AccessReach Liman MYS web/API endpoint
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DeliveryCraft forged JWT bypassing signature check
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ExploitSubmit token to authenticate as trusted user
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ExecutionImpersonate administrator / read sensitive data
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ImpactExecute management actions on hosts
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A04:2025 - Cryptographic Failures
ASVS 5.0
V11 - Cryptography Signature verification
|
| Exploitation Conditions | Exploitation requires network access to the Liman MYS application's authentication/token-handling surface (the JWT-processing endpoint) on a vulnerable build before release.Master.1107; the attacker must construct a token that abuses the improper signature check (per the 'Jwt Attack' tag, e.g. algorithm confusion or a missing/weak signature check). No valid credentials, no privileges (PR:N) and no user interaction (UI:N) are needed per the CVSS vector. Limiting factors: only instances reachable by the attacker are exposed, NVD rates the attack complexity HIGH (AC:H) implying some non-trivial condition such as knowledge of a key, token structure, or a specific misconfiguration may be required, and instances behind network segmentation or with hardened token validation at a proxy are harder to reach. |
| Impact | The NVD CVSS is 8.1 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H): remotely reachable, no privileges or user interaction, but rated high attack complexity. There is tension in the signals: classic JWT signature-verification bypasses (alg confusion, alg:none) are typically LOW complexity once known, so AC:H may overstate the difficulty - independently I assess AC:L, which would push severity higher. There is no EPSS score, no SSVC decision, and no POC in the provided data, and it is not in CISA KEV, so there is currently no evidence of active or automatable exploitation. Net: a genuinely high-severity auth/spoofing flaw by construction, but real-world urgency depends on deployment footprint (niche product) and whether an exploit surfaces; treat as high-priority patch for any Liman MYS operator, monitor for POC. |
| Exploit ScenarioDerived | An attacker who can reach the Liman MYS web interface crafts a forged token (e.g., a JWT with a manipulated algorithm or unsigned/attacker-signed payload) that the server accepts as authentic due to improper signature verification, impersonating a trusted or administrative user. With that forged identity the attacker reads sensitive data and issues management actions. No public exploit is identified at time of analysis, so this reflects the plausible attack path rather than an observed campaign. |
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Alert meAnalysisAIv1 – Jul 07, 2026
Signature verification bypass in HAVELSAN Liman MYS (versions before release.Master.1107) lets remote attackers forge the source/authenticity of data - tagged as a JWT attack - enabling identity spoofing and likely authentication bypass. Per CVSS the vector is network-based and unauthenticated (AV:N/PR:N) with high impact to confidentiality and integrity. No public exploit is identified at time of analysis and it is not on CISA KEV.
RemediationAI
Vendor-released patch: upgrade Liman MYS to release.Master.1107 or later, which corrects the signature-verification flaw; this is the primary and recommended remediation. Consult the USOM advisory at https://siberguvenlik.gov.tr/guvenlik-bildirimleri/detay/tr-26-0504 and the HAVELSAN/Liman release notes to confirm the fixed build for your channel. If immediate patching is not possible, compensating controls include restricting network reachability of the Liman MYS web/API interface to trusted management networks or VPN (reduces the AV:N exposure at the cost of remote-admin convenience), rotating and strengthening JWT signing secrets and enforcing an explicit allow-list of signing algorithms at any reverse proxy/WAF if configurable (mitigates alg-confusion/alg:none forgery but may break clients using other algorithms), and invalidating existing sessions/tokens after upgrade. These are stopgaps only - the signature-verification defect itself is fixed solely by the vendor patch.
Affected VersionsENISA
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Technical ContextAI · show details
Liman MYS (Management System) is a HAVELSAN-developed centralized Linux/server management panel used to administer hosts and services through a web interface. The root cause is CWE-347, Improper Verification of Cryptographic Signature: the application accepts data whose cryptographic signature is not correctly validated. The 'Jwt Attack' tag strongly implies the weakness lies in JSON Web Token handling - for example accepting the 'alg:none' header, RS256/HS256 algorithm confusion, or otherwise failing to enforce a trusted signing key - which would allow an attacker to mint tokens the server treats as genuine and thereby impersonate a legitimate (potentially administrative) principal.
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Severity by source
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Network-reachable JWT forgery needs no auth or interaction (AV:N/PR:N/UI:N); typical alg-confusion bypasses are low complexity (AC:L, versus NVD's AC:H); spoofing yields high C/I but no clear direct availability impact (A:N).
Primary rating from Vendor (usom).
CVSS VectorVendor: usom
DescriptionCVE.org
Improper verification of cryptographic signature vulnerability in HAVELSAN Inc. Liman MYS allows Fake the Source of Data.
This issue affects Liman MYS: before release.Master.1107.
Executive ViewAI
HAVELSAN Liman MYS contains a JWT signature verification bypass (CVE-2026-11348) enabling unauthenticated remote attackers to forge authentication tokens and impersonate legitimate users. Organizations operating this platform face immediate risk of unauthorized system access, data exposure, and identity-based attacks without cryptographic validation of user credentials. No vendor patch is currently available.
No vendor-released patch identified at time of analysis. Interim mitigations: isolate HAVELSAN Liman MYS from internet-facing networks using segmentation or firewall rules; enforce multi-factor authentication on dependent systems and administrative accounts; implement continuous monitoring for JWT signature anomalies and spike in failed authentication attempts; disable JWT-based API endpoints where operationally feasible; require re-authentication for sensitive transactions until patching is complete.
Threat Intelligence Overview
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.
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EUVD-2026-42034
GHSA-cmjg-6q27-6fr4
NVD
CVE.org
EPSS
Vulnrichment
Exploit-DB