---
id: CVE-2026-25551
title: "Seagull Software BarTender 2021 R1 through 12.0.1\_contains an insecure deserialization vulnerability that allows low-privileged local users to escalate privileges"
summary: "Seagull Software BarTender 2021 R1 through 12.0.1\_contains an insecure deserialization vulnerability that allows low-privileged local users to escalate privileges. The DataServiceSingleton .NET Remoting endpoint is bound to localhost on …"
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-502
published: '2026-06-04'
updated: '2026-09-02'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-25551'
references:
  - url: 'https://gist.github.com/VAMorales/dde5b1c0415a8505ccd6fafdb095a618'
    label: disclosure@vulncheck.com
  - url: 'https://portal.seagullscientific.com/downloads/bartender'
    label: disclosure@vulncheck.com
  - url: >-
      https://trust.seagullsoftware.com/?tcuUid=55ed135f-683c-4e9b-a59d-7d4373c0ac7e
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/seagull-software-bartender-deserialization-privilege-escalation-via-net-remoting-service
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.00357
epssPercentile: 0.26795
ingestedAt: '2026-09-02T17:48:01.635Z'
---

## Overview

Seagull Software BarTender 2021 R1 through 12.0.1 contains an insecure deserialization vulnerability that allows low-privileged local users to escalate privileges. The DataServiceSingleton .NET Remoting endpoint is bound to localhost on TCP port 7375 via BtSystem.Service.exe, limiting the attack surface to local access only. The endpoint is configured with BinaryServerFormatterSinkProvider and TypeFilterLevel set to Full. A low-privileged local attacker can send YSoSerial.NET-generated BinaryFormatter payloads to the localhost-bound endpoint to achieve code execution as NT AUTHORITY\\\\SYSTEM. The vulnerability was corrected in BarTender 12.1, released on August 14, 2026. Users should upgrade to BarTender 12.1 or later.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.