# 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.

- **Severity:** Not scored
- **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:** Yes
- **Published:** 14 May 2026
- **Updated:** 15 May 2026
- **Also known as:** GHSA-v8vw-gw5j-w7m6, GO-2026-5658

## 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 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2026-44427?

3 open source packages ship an affected version, including github.com/modelcontextprotocol/registry.


| Package | Ecosystem | 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44427 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44427 exists.

Affected packages and fixed versions:
- github.com/modelcontextprotocol/registry (Go): affected from 1.1.0; fixed in 1.7.5
- github.com/modelcontextprotocol/registry (Go): affected from 1.1.0; fixed in 1.7.5
- github.com/modelcontextprotocol/registry (Go): affected from 1.1.0; fixed in 1.7.5

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-2026-44427/ (Markdown: https://insights.sbomify.com/CVE-2026-44427/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44427
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44427
- OSV: https://osv.dev/vulnerability/CVE-2026-44427

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-44427/
Summaries are generated and may contain mistakes; the official description above is the record.