EUVD-2026-42034
GHSA-cmjg-6q27-6fr4
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
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
1DescriptionCVE.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.
AnalysisAI
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. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | 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. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | 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. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | 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. … |
| Remediation | 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. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Inventory all HAVELSAN Liman MYS deployments (versions before release.Master.1107) and classify by business criticality; contact HAVELSAN support to confirm patch timeline and request interim guidance. …
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