CVE-2026-44427 MCP Registry: Open Redirect
An attacker can redirect users to malicious external sites via crafted URLs in the MCP Registry, potentially facilitating phishing attacks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-44427?
CVE-2026-44427 is a vulnerability in modelcontextprotocol registry, published on 14 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
The MCP Registry provides MCP clients with a list of MCP servers, like an app store for MCP servers. From 1.1.0 to 1.7.4, the TrailingSlashMiddleware in internal/api/server.go is vulnerable to an open redirect attack. An attacker can craft a URL with a protocol-relative path (e.g., //evil.com/) that, after trailing slash removal, results in a Location header of //evil.com — which browsers interpret as an absolute URL to an external domain. This vulnerability is fixed in 1.7.5.
Weakness: CWE-601
Which versions are affected by CVE-2026-44427?
3 open source packages ship an affected version, including github.com/modelcontextprotocol/registry.
| Package | Affected | Fixed in |
|---|---|---|
github.com/modelcontextprotocol/registry Go | From 1.1.0 | 1.7.5 |
github.com/modelcontextprotocol/registry Go | From 1.1.0 | 1.7.5 |
github.com/modelcontextprotocol/registry Go | From 1.1.0 | 1.7.5 |
How do I fix CVE-2026-44427?
Upgrade github.com/modelcontextprotocol/registry to 1.7.5 or later.
Is CVE-2026-44427 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44427 exists.
Sources
Also known as GHSA-v8vw-gw5j-w7m6, GO-2026-5658.