CVE-2026-59104: UgCS server before 6.2 contains an authentication bypass in the HCI protocol login handler (LoginHandler) expo

Q: How do I fix CVE-2026-59104?

ugcs: upgrade to 6.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-59104 being exploited?

CVE-2026-59104 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-59104 affect?

CVE-2026-59104 affects ugcs. Severity is critical (CVSS 9.8). UgCS server before 6.2 contains an authentication bypass in the HCI protocol login handler (LoginHandler) exposed on TCP port 3334. When the user database contains exactly one user (the default single-operator installation), a LoginRequest

Q: How urgent is CVE-2026-59104?

Priority 34/100. Critical severity

This month

CRITICAL 9.8UPGRADE

CVE-2026-59104 is a critical-severity flaw (CVSS 9.8) affecting ugcs. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

UgCS server before 6.2 contains an authentication bypass in the HCI protocol login handler (LoginHandler) exposed on TCP port 3334. When the user database contains exactly one user (the default single-operator installation), a LoginRequest with empty userLogin and userPassword fields is interpreted as \"use the only user\" rather than as invalid credentials, and the server returns a fully authenticated session. Because the service listens on all

Why this priority

Critical severity

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
EPSS exploit chance	n/a
CISA exploited list	No
Weakness	CWE-287
Published	2026-11-06
Last modified	2026-11-06

Publisher (CNA): ENISA · Vendor: sph engineering · Source: CVE Program record (NVD analysis pending)

Last updated 2026-11-06 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-11-06 21:41 UTCPublished CVE record published
2026-11-06 21:41 UTCUpdated Record last modified

sph engineering ugcs UPGRADE

Affected: < 6.2

Fixed in: 6.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy ugcs || rpm -q ugcs || ugcs --version

2. UPGRADE to 6.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade ugcs

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ugcs

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-59104?

ugcs: upgrade to 6.2. Exact commands for each OS are on this page.

Is CVE-2026-59104 being exploited?

CVE-2026-59104 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-59104 affect?

CVE-2026-59104 affects ugcs. Severity is critical (CVSS 9.8). UgCS server before 6.2 contains an authentication bypass in the HCI protocol login handler (LoginHandler) exposed on TCP port 3334. When the user database contains exactly one user (the default single-operator installation), a LoginRequest

How urgent is CVE-2026-59104?

Priority 34/100. Critical severity

References

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