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

> Unauthenticated attackers can achieve remote code execution as SYSTEM via insecure .NET Remoting deserialization in PACSgear MediaWriter.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Jul 2026
- **Updated:** 1 Jul 2026
- **Also known as:** GHSA-9h7v-mf98-p6r6

## What is CVE-2026-58127?

CVE-2026-58127 is a critical unsafe deserialization vulnerability in Hyland PACSgear MediaWriter, published on 1 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-502 (Deserialization of Untrusted Data), CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-58127?

It affects 1 product.


Products: Hyland Pacsgear.

## How do I fix CVE-2026-58127?

No fix has been published for CVE-2026-58127 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-58127 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-58127 exists.

## Other vulnerabilities in Hyland PACSgear MediaWriter

- [CVE-2026-58126](https://insights.sbomify.com/CVE-2026-58126/): PACSgear PACS Scan 5.2.1 Unauthenticated RCE via .NET Remoting TCP Service (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-58127 and fix it if it is affected.

What it is: CVE-2026-58127 is a critical unsafe deserialization vulnerability in Hyland PACSgear MediaWriter, published on 1 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-58127 exists.

Affected product: Hyland PACSgear MediaWriter. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-58127/ (Markdown: https://insights.sbomify.com/CVE-2026-58127/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-58127
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-58127
- OSV: https://osv.dev/vulnerability/CVE-2026-58127

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-58127/
Summaries are generated and may contain mistakes; the official description above is the record.