# ToolHive: SSRF guard misses IPv6 NAT64 ranges (64:ff9b::/96, 64:ff9b:1::/48), allowing metadata/internal access behind a NAT64 gateway

Advisory record · `GHSA-pph6-vfjv-vpjw`

- **Identifiers:** `GHSA-pph6-vfjv-vpjw` · `CVE-2026-54450` · `GO-2026-5996`
- **State:** Confirmed
- **Severity:** CVSS 2.9 Low
- **Critical:** No
- **Weakness (CWE):** [CWE-918](https://cwe.mitre.org/data/definitions/918.html)
- **Tags:** [Server-side request forgery (SSRF)](https://agentprime.io/advisories/tag/ssrf.md)
- **Published:** 15 Jul 2026
- **Updated:** 21 Jul 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 15 Jul 2026, 21:51 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `github.com/stacklok/toolhive` (Go): affected `<0.29.1`; fixed in `0.29.1`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> The ToolHive package github.com/stacklok/toolhive, versions before 0.29.1, has an SSRF guard (IsPrivateIP) that does not recognize the IPv6 NAT64 ranges 64:ff9b::/96 and 64:ff9b:1::/48, so NAT64-encoded internal addresses such as those for the cloud metadata address are treated as public. An attacker who can supply a URL reaching this guard, such as an OAuth client ID metadata URL, can make ToolHive probe internal addresses when deployed behind a NAT64 gateway, though the source describes this as a blind reachability probe rather than credential theft. Upgrade to version 0.29.1.

Written 6 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 2.9 Low, CVSS 4.0: `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`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0033, the 26th percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:59 UTC: First seen by agentprime
- 31 Oct 2026, 14:59 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-pph6-vfjv-vpjw)

## Sources

- [GitHub Advisory Database: GHSA-pph6-vfjv-vpjw](https://github.com/advisories/GHSA-pph6-vfjv-vpjw)
- [OSV: GHSA-pph6-vfjv-vpjw](https://osv.dev/vulnerability/GHSA-pph6-vfjv-vpjw)
- <https://github.com/stacklok/toolhive/security/advisories/GHSA-pph6-vfjv-vpjw>
- <https://github.com/stacklok/toolhive>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-pph6-vfjv-vpjw>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-pph6-vfjv-vpjw/>. Everything for agents: <https://agentprime.io/llms.txt>.