Model Context Protocol Python SDK: HTTP client transports followed cross-origin redirects carrying custom headers and bodies
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 1.30.0, 2.2.0
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
The Model Context Protocol Python SDK, which is used by applications acting as MCP clients or connecting to MCP servers over HTTP, is affected. When these client connections follow redirects to a different website, they can send along custom credential headers and, for certain redirects, the request body, so an attacker who controls where a trusted endpoint redirects could receive that sensitive information.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original description
The Model Context Protocol Python SDK is the official Python SDK for Model Context Protocol servers and clients. From 1.8.0 until 1.30.0 and 2.2.0, streamable_http_client, streamablehttp_client, sse_client, ClientSessionGroup, OAuth, and create_mcp_http_client client paths enable follow_redirects and follow redirects to a different origin, forwarding caller-supplied custom credential headers and, for 307 or 308 responses, the request body. An attacker who can influence a trusted endpoint's redirect destination can receive that material. This issue is fixed in versions 1.30.0 and 2.2.0.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- modelcontextprotocol python-sdk
From 1.8.0 · fixed in 1.30.0; From 2.0.0 · fixed in 2.2.0
- mcpPyPI
From 2.0.0 · fixed in 2.2.0
- mcpPyPI
From 1.8.0 · fixed in 1.30.0