CVE-2026-111769

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-10-16 17:52 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-11-05 22:17 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-11-09 19:16 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.4% in the next 30 days (EPSS).
• Severity: 6.5 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-11-05 22:17 UTC

Last modified

2026-11-09 19:16 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-200 · Information exposure

Record status

Received

Attack profile CVSS 3.1 · 6.5

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

Low

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-111769.md and follow it. Check whether this project is affected by CVE-2026-111769. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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