Answer in brief
CVE-2026-111769 records a Medium severity (CVSS 6.5) vulnerability in Model Context Protocol TypeScript SDK: HTTP client transports and OAuth requests followed cross-origin redirects and re-sent custom headers and request bodies. The current sources do not mark it as known exploited. The current feed maps @modelcontextprotocol/client (generic), @modelcontextprotocol/sdk (generic), modelcontextprotocol/typescript-sdk (generic), @modelcontextprotocol/client (npm) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps @modelcontextprotocol/client (generic), @modelcontextprotocol/sdk (generic), modelcontextprotocol/typescript-sdk (generic), @modelcontextprotocol/client (npm) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| @modelcontextprotocol/clientgeneric | >=2.0.0 <2.3.0 | 2.3.0 |
| @modelcontextprotocol/sdkgeneric | <1.32.0 | 1.32.0 |
| modelcontextprotocol/typescript-sdkgeneric | <1.32.0 | 1.32.0 |
| @modelcontextprotocol/clientnpm | >=2.0.0,<2.3.0 | 2.3.0 |
| @modelcontextprotocol/sdknpm | <1.32.0 | 1.32.0 |
Published upstream
Nov 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 20, 2026
The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. Prior to 1.32.0 in @modelcontextprotocol/sdk and from 2.0.0 until 2.3.0 in @modelcontextprotocol/client, the HTTP client transports and OAuth client requests followed redirects to a different origin while retaining custom request headers and, for HTTP 307 or 308 responses, request bodies. The affected surfaces are StreamableHTTPClientTransport, SSEClientTransport, and OAuth client functions such as auth(). The trigger is an HTTP redirect to another origin. Custom headers and mcp-session-id can be re-sent to the redirected origin. HTTP 307 and 308 redirects can also re-send the request body. OAuth request bodies can contain refresh_token and client_secret values. Current runtimes already strip the Authorization header across origins. stdio clients do not use the affected HTTP path. A malicious or compromised MCP or authorization server could therefore receive API keys, session identifiers, OAuth refresh tokens, or OAuth client secrets. Restoring unrestricted redirect following after upgrading restores the exposure. This issue is fixed in @modelcontextprotocol/sdk 1.32.0 and @modelcontextprotocol/client 2.3.0.
Quoted source text, attributed separately from HOL analysis.