Authentication Bypass in UgCS Server by UGCS
CVE-2026-59104

9.3CRITICAL

Key Information:

Vendor

Sph Engineering

Status
Ugcs
Vendor
CVE Published:
6 November 2026

What is CVE-2026-59104?

The UgCS server prior to version 6.2 is vulnerable to an authentication bypass through its HCI protocol login handler, which is accessible on TCP port 3334. In scenarios where the user database is configured with a single user (typical of default installations), a malformed LoginRequest with empty userLogin and userPassword fields may be misinterpreted as a valid request for the existing user. As a result, an attacker can exploit this loophole to gain unauthorized access and initiate privileged commands, including the control of connected drones and the uploading of flight routes. This vulnerability poses a significant risk due to the default non-encrypted state of the service, allowing exploitation by any remote party with network access.

Affected Version(s)

UgCS Windows 0 < 6.2

References

https://www.ugcs.com/
product
https://offseq.com/en/research/ugcs-cve-2026-59104/
third-party-advisory

CVSS V4

Score:
9.3
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

OffSeq Cybersecurity
CERT.LV
.