# CVE-2026-79749: MCPHub: SSRF Guard Bypass via IPv6 Transition Addresses in URL Validation

> Attackers can bypass SSRF protections in MCPHub by using IPv6 transition addresses to access internal network resources.

- **Severity:** High 7.6 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 31 Aug 2026
- **Updated:** 31 Aug 2026
- **Also known as:** GHSA-pr4x-3pc7-2fhw

## What is CVE-2026-79749?

CVE-2026-79749 is a high-severity server-side request forgery vulnerability in samanhappy mcphub, published on 31 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

MCPHub is a unified hub for centrally managing and dynamically orchestrating multiple MCP servers/APIs into separate endpoints with flexible routing strategies. Prior to version 1.0.32, MCPHub's SSRF guard in src/utils/ssrf.ts uses a custom isBlockedIpv6 function that only checks for loopback, link-local, unique-local, IPv4-mapped, and IPv4-compatible IPv6 addresses. IPv6 transition address families -- NAT64 (64:ff9b::/96), 6to4 (2002::/16), and Teredo (2001::/32) -- are not checked. An attacker who can specify a URL for an MCP server connection can encode a private IPv4 address inside one of these IPv6 forms to bypass the SSRF guard and reach internal infrastructure. This issue has been patched in version 1.0.32.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-79749?


## How do I fix CVE-2026-79749?

No fix has been published for CVE-2026-79749 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-79749 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-79749 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-79749 and fix it if it is affected.

What it is: CVE-2026-79749 is a high-severity server-side request forgery vulnerability in samanhappy mcphub, published on 31 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-79749 exists.

Affected product: samanhappy mcphub. 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-2026-79749/ (Markdown: https://insights.sbomify.com/CVE-2026-79749/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-79749
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-79749
- OSV: https://osv.dev/vulnerability/CVE-2026-79749

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-79749/
Summaries are generated and may contain mistakes; the official description above is the record.