CVE-2026-25551 Seagull Software BarTender Deserialization Privilege Escalation via .NET Remoting Service
Local attackers can exploit insecure .NET Remoting deserialization in BarTender to execute arbitrary code with SYSTEM privileges.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-25551?
CVE-2026-25551 is a high-severity unsafe deserialization vulnerability in Seagull Software, LLC. BarTender 2021, published on 4 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-502
Which versions are affected by CVE-2026-25551?
How do I fix CVE-2026-25551?
No fix has been published for CVE-2026-25551 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-25551 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-25551 exists.
Sources
Also known as GHSA-g42f-xxvf-qj27.