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.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
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
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.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-79749 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-79749 exists.
Sources
Also known as GHSA-pr4x-3pc7-2fhw.