CVE-2025-66416
- Source
- https://nvd.nist.gov/vuln/detail/CVE-2025-66416
- Import Source
- https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-66416.json
- JSON Data
- https://api.test.osv.dev/v1/vulns/CVE-2025-66416
- Aliases
- Published
- 2025-12-02T18:14:28.310Z
- Modified
- 2025-12-06T14:10:26.920070Z
- Severity
-
- 7.6 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N CVSS Calculator
- Summary
- DNS Rebinding Protection Disabled by Default in Model Context Protocol Python SDK for Servers Running on Localhost
- Details
-
The MCP Python SDK, called
mcpon PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to version 1.23.0, tThe Model Context Protocol (MCP) Python SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication using FastMCP with streamable HTTP or SSE transport, and has not configured TransportSecuritySettings, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user in those limited circumstances. Note that running HTTP-based MCP servers locally without authentication is not recommended per MCP security best practices. This issue does not affect servers using stdio transport. This vulnerability is fixed in 1.23.0. - Database specific
{ "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66416.json", "cna_assigner": "GitHub_M", "cwe_ids": [ "CWE-1188" ] }- References
-
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66416.json
- https://github.com/modelcontextprotocol/python-sdk/commit/d3a184119e4479ea6a63590bc41f01dc06e3fa99
- https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-9h52-p55h-vw2f
- https://nvd.nist.gov/vuln/detail/CVE-2025-66416
Affected packages
Git / github.com/modelcontextprotocol/python-sdk
Affected ranges
- Type
- GIT
- Repo
- https://github.com/modelcontextprotocol/python-sdk
- Events
-
Introduced0 Unknown introduced commit / All previous commits are affectedFixed