GHSA-v8vw-gw5j-w7m6

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Source
https://github.com/advisories/GHSA-v8vw-gw5j-w7m6
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-v8vw-gw5j-w7m6/GHSA-v8vw-gw5j-w7m6.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-v8vw-gw5j-w7m6
Aliases
  • CVE-2026-44427
Related
Published
2026-05-08T17:02:12Z
Modified
2026-05-10T04:44:28.963068849Z
Severity
  • 5.7 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P CVSS Calculator
Summary
MCP Registry has open redirect via protocol-relative path in trailing-slash middleware
Details

Summary

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.

Details

The TrailingSlashMiddleware strips trailing slashes from request paths and issues a 308 Permanent Redirect to the cleaned path. However, it does not validate or sanitize the resulting path before using it as the redirect target.

When a request is made with a path like //evil.com/, the middleware processes it as follows:

PoC

  1. Start the registry server locally or identify a deployed instance
  2. Send a request with a double-slash path followed by an external domain: curl -v https://<registry-host>//evil.com/ <img width="3066" height="969" alt="image" src="https://github.com/user-attachments/assets/a5305f00-29bf-4708-952a-478d608f2074" />
  3. Observe the 308 Permanent Redirect response with Location: //evil.com:
  4. When accessed in a browser, the user is redirected to https://evil.com

Impact

Phishing: Attackers can abuse the trusted registry domain to redirect users to credential-harvesting pages Malware distribution: Redirect users to sites serving malicious downloads Trust abuse: Links originating from the official MCP Registry domain carry implicit trust

Database specific 
{
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-08T17:02:12Z",
    "nvd_published_at": null,
    "severity": "MODERATE",
    "cwe_ids": [
        "CWE-601"
    ]
}
References

Affected packages

Go / github.com/modelcontextprotocol/registry

Package

Name
github.com/modelcontextprotocol/registry
View open source insights on deps.dev
Purl
pkg:golang/github.com/modelcontextprotocol/registry

Affected ranges

Type
SEMVER
Events
Introduced
1.1.0
Fixed
1.7.5

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-v8vw-gw5j-w7m6/GHSA-v8vw-gw5j-w7m6.json"