What is CVE-2026-25550?

CVE-2026-25550 is a critical-severity vulnerability in Seagull Software, Llc. Bartender 2010, classified under Missing Authentication for Critical Function. CVSS score: 9.8/10. Published 2026-06-04.

How severe is CVE-2026-25550?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Seagull Software, Llc. Bartender 2010

CVE-2026-25550

Seagull Software BarTender 2010, 2016, and 2019 contain an unauthenticated remote code execution vulnerability in the .NET Remoting service exposed on TCP port 7375 via BtSystem.Service.exe. The service registers an unauthenticated singleton endpoint — BarTenderSystem for BarTender 2016 <= R9, and DataServiceSingleton for BarTender 2019 <= R10 — configured with BinaryServerFormatterSinkProvider and TypeFilterLevel set to Full. An unauthenticated remote attacker can exploit .NET Remoting object unmarshalling to read or write arbitrary files on the server using the .NET WebClient class, or coerce NTLMv2 authentication by supplying a UNC path to an attacker-controlled server, enabling sensitive credential disclosure, remote code execution, or lateral movement depending on service account privileges and network environment. The service runs in the context of NT AUTHORITY\\SYSTEM. This vulnerability is corrected in BarTender 12.0.1. Users of affected releases should upgrade to BarTender 12.0.1 or later.

Vulnerability class: Broken Authentication

Published 2026-06-04 · last modified 2026-09-16.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.014 (72.0th percentile), scored 2026-10-03.

Low probability of exploitation in the next 30 days, but still tracked. 72nd percentile — 72.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.014 · change: +0.005

Affected products

Seagull Software, Llc. Bartender 2010 — versions 0
Seagull Software, Llc. Bartender 2016 — versions 0
Seagull Software, Llc. Bartender 2019 — versions 0

Weakness classification (CWE)

References

portal.seagullscientific.com/downloads/bartender (product)
www.vulncheck.com/advisories/seagull-software-bartender-unauthenticated-rce-via… (third-party-advisory)
trust.seagullsoftware.com/ (vendor-advisory, patch)
gist.github.com/VAMorales/dde5b1c0415a8505ccd6fafdb095a618 (technical-description, exploit)

Frequently asked questions

What is CVE-2026-25550?: CVE-2026-25550 is a critical-severity vulnerability in Seagull Software, Llc. Bartender 2010, classified under Missing Authentication for Critical Function. CVSS score: 9.8/10. Published 2026-06-04.
How severe is CVE-2026-25550?: Critical severity. CVSS v3 base score is 9.8 out of 10.