# CVE-2026-79749: MCPHub SSRF guard bypass in IPv6 transition address handling

Source: https://junglewise.ai/threats/cve-2026-79749-mcphub-ssrf-guard-bypass-in-ipv6-transition-address-handling  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-31. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-79749 · Severity: info · Published 2026-08-31

MCPHub is a hub for managing and routing connections to multiple MCP servers. An attacker who can control server URLs can bypass security restrictions by using special IPv6 address formats to reach internal systems that should be inaccessible. This could allow compromise of internal infrastructure, data exfiltration, or lateral movement within a network.

Technologies: [Samanhappy Mcphub](https://junglewise.ai/threats/technologies/mcphub). Vendors: [Samanhappy](https://junglewise.ai/threats/vendors/samanhappy).

## Quick answers

**Is CVE-2026-79749 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-79749 being exploited in the wild.

**How severe is CVE-2026-79749?** Informational severity, published 31 August 2026.

**Which products and versions are affected?** Samanhappy Mcphub before 1.0.32.

**Is there a fix for CVE-2026-79749?** A patch was published on 2026-08-23: Fix merged in PR #1069 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-79749 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-79749?** Check whether you run Samanhappy Mcphub at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

MCPHub's SSRF (Server-Side Request Forgery) guard in src/utils/ssrf.ts implements a custom isBlockedIpv6 function that is incomplete. It checks only for loopback, link-local, unique-local, IPv4-mapped, and IPv4-compatible IPv6 addresses but fails to block IPv6 transition address families: NAT64 (64:ff9b::/96 and 64:ff9b:1::/48), 6to4 (2002::/16), Teredo (2001::/32), site-local (fec0::/10), and multicast (ff00::/8). An attacker can specify an MCP server URL using these transition formats to encode private IPv4 addresses, thereby bypassing the SSRF blocklist and reaching internal infrastructure. The vulnerability is network-reachable and requires only the ability to specify a server URL. Patches are available in version 1.0.32 and later.

## Affected products

- samanhappy MCPHub before 1.0.32

## Timeline

- 2026-08-31: disclosed
- 2026-08-23: patched: Fix merged in PR #1069

## References

- [https://github.com/samanhappy/mcphub/commit/2b10ae36112ce68deebf910b22505d44efcef552](https://github.com/samanhappy/mcphub/commit/2b10ae36112ce68deebf910b22505d44efcef552)
- [https://github.com/samanhappy/mcphub/pull/1069](https://github.com/samanhappy/mcphub/pull/1069)

## Related threats

- [samanhappy MCPHub credential exfiltration via passthroughHeaders](https://junglewise.ai/threats/cve-2026-120323-a-security-flaw-has-been-discovered-in-samanhappy-mcphub-up-to-1)
- [samanhappy MCPHub privilege management in template import](https://junglewise.ai/threats/cve-2026-94047-a-security-vulnerability-has-been-detected-in-samanhappy-mcphub)
- [MCPHub OAuth 2.0 authentication bypass in authorization server](https://junglewise.ai/threats/cve-2026-90474-mcphub-oauth-2-0-authentication-bypass-in-authorization-server)
- [MCPHub horizontal privilege escalation in tool execution API](https://junglewise.ai/threats/cve-2026-79750-mcphub-horizontal-privilege-escalation-in-tool-execution-api)
- [MCPHub privilege escalation in server configuration endpoints](https://junglewise.ai/threats/cve-2026-79748-mcphub-privilege-escalation-in-server-configuration-endpoints)