{"id":"GHSA-v8vw-gw5j-w7m6","revision":"0b7657cc0f87419a86edd7253bd772c8","records":[{"revision":"0b7657cc0f87419a86edd7253bd772c8","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GHSA-v8vw-gw5j-w7m6","aliases":["CVE-2026-44427","GO-2026-5658"],"title":"MCP Registry has open redirect via protocol-relative path in trailing-slash middleware","description":"### Summary\nThe 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.\n\n### Details\nThe 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.\n\nWhen a request is made with a path like //evil.com/, the middleware processes it as follows:\n\n### PoC\n1. Start the registry server locally or identify a deployed instance\n2. Send a request with a double-slash path followed by an external domain:\n`curl -v https://<registry-host>//evil.com/`\n<img width=\"3066\" height=\"969\" alt=\"image\" src=\"https://github.com/user-attachments/assets/a5305f00-29bf-4708-952a-478d608f2074\" />\n3. Observe the 308 Permanent Redirect response with Location: //evil.com:\n4. When accessed in a browser, the user is redirected to https://evil.com\n\n\n\n### Impact\n**Phishing**: Attackers can abuse the trusted registry domain to redirect users to credential-harvesting pages\n**Malware distribution**: Redirect users to sites serving malicious downloads\n**Trust abuse:** Links originating from the official MCP Registry domain carry implicit trust","state":0,"publishedAt":"2026-05-08T17:02:12+00:00","modifiedAt":"2026-09-10T03:50:47.559592+00:00","affected":[{"ecosystem":"Go","name":"github.com/modelcontextprotocol/registry","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"1.1.0"},{"kind":"fixed","version":"1.7.5"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"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","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/modelcontextprotocol/registry/security/advisories/GHSA-v8vw-gw5j-w7m6","https://nvd.nist.gov/vuln/detail/CVE-2026-44427","https://github.com/modelcontextprotocol/registry/pull/1227","https://github.com/modelcontextprotocol/registry/commit/1201cbd82b2cf6d4b56edfc05c763059a12f9fdb","https://github.com/modelcontextprotocol/registry","https://github.com/modelcontextprotocol/registry/releases/tag/v1.7.5"],"sourceUrl":"https://github.com/advisories/GHSA-v8vw-gw5j-w7m6","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-v8vw-gw5j-w7m6","identifiers":["GHSA-v8vw-gw5j-w7m6","CVE-2026-44427","GO-2026-5658"]},"retained":false,"historicalAffected":[]}],"coverage":[]}