ToolHive: SSRF in remote MCP server authentication discovery (host-side, bypasses container isolation)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.9 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P · score source

EPSS

• CVE-2026-58196: 0.43% estimated exploitation activity in the next 30 days; percentile 37.20 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Security Advisory: SSRF in remote MCP server authentication discovery Severity: High. CWE: CWE-918. Affected: ToolHive through the latest release v0.29.3 and current main (HEAD b672d82f, 2026-06-12; re-verified 2026-06-14). FetchResourceMetadata and the discovery clients remain unguarded; no commits to pkg/auth/discovery or pkg/auth/remote address this. Originally identified at commit 05f11b53; all line references below are against HEAD b672d82f. Summary ToolHive's remote MCP server authentication discovery issues outbound HTTP requests to URLs the remote MCP server controls, with no private-IP or loopback guard and no restriction on redirects. ToolHive's core security model treats every MCP server as untrusted: the README states it "runs every MCP server in an isolated container" with "no local credentials," and it ships an egress proxy for network isolation. This discovery code runs host-side, in the ToolHive process, before and outside that per-server container sandbox. A…

Published by the source

15 Jul 2026, 23:41 UTC

Last modified by the source

15 Jul 2026, 23:41 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-pr64-jmmf-jp54

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# Patch Next advisory brief: CVE-2026-58196

Advisory: ToolHive: SSRF in remote MCP server authentication discovery (host-side, bypasses container isolation)
IDs: CVE-2026-58196, GHSA-pr64-jmmf-jp54
Record: https://patchnext.com/advisories/cve-2026-58196 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/stacklok/toolhive 0.31.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/stacklok/toolhive: affected < 0.31.0; fixed in 0.31.0

## Suggested inspection (read-only)
- Go github.com/stacklok/toolhive: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/stacklok/toolhive.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-pr64-jmmf-jp54 (GitHub-reviewed advisory GHSA-pr64-jmmf-jp54 lists affected ranges: Go github.com/stacklok/toolhive >=0 <0.31.0)

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