CVE-2026-25551: Seagull Software, LLC BarTender 2021 · Deserialization of Untrusted Data
Affects Seagull Software, LLC BarTender 2021Source CVE Database V5
Not known to be exploited · CVSS 8.5 High.
Data as of 29 Oct 2026, 19:04 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 4 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Seagull Software, LLC.BarTender 2021 | Affected
| Fixed in– |
AI-suggested
Until a patch or official fix is available, restrict local access to the affected service and monitor for suspicious local activity targeting TCP port 7375. Consider disabling or restricting the BtSystem.Service.exe if feasible.
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.
References
- gist.github.com/VAMorales/dde5b1c0415a8505ccd6fafdb095a618 (opens in a new tab)
- portal.seagullscientific.com/downloads/bartender (opens in a new tab)
- vulncheck.com/advisories/seagull-software-bartender-deserialization-privilege-escalation-via-net-remoting-service (opens in a new tab)
- trust.seagullsoftware.com (opens in a new tab)