What’s Vulnerable › Vulnerabilities

CVE-2026-58127: PACSgear MediaWriter 5.2.1 Unauthenticated RCE via .NET Remoting TCP Service

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-07-01 · updated 2026-10-25
• Weakness: CWE-306

Description

PACSgear MediaWriter 5.2.1 exposes a .NET Remoting TCP service on port 9000 via PacsgearMediaServerEngine.dll, registered with ObjectURIs RemoteObj and UIRemoteObj, without any authentication requirement. By exploiting the MarshalByRefObject object unmarshalling technique and implementing .NET WebClient class methods, an unauthenticated remote attacker can read and write arbitrary files on the host filesystem. The ObjectURIs are identical across all installations by default. Chaining the arbitrary file write primitive with DLL hijacking opportunities in the MediaWriter service (which runs as NT Authority\\SYSTEM and loads missing DLLs such as CRYPTBASE.DLL from the application directory) enables unauthenticated remote code execution as SYSTEM upon service restart.

Affected products

• Hyland PACSgear MediaWriter: through 5.2.1

References

• https://gist.github.com/VAMorales/dc679ecab30b7045fa07bf3249a034d8
• https://www.hyland.com/en/solutions/products/pacsgear
• https://www.vulncheck.com/advisories/pacsgear-mediawriter-unauthenticated-rce-via-net-remoting-tcp-service

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