# CVE-2026-111769: Model Context Protocol TypeScript SDK: HTTP client transports and OAuth requests followed cross-origin redirects and re-sent custom headers and request bodies

Status: published. Published: 2026-11-05. Updated: 2026-11-09.

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.

## Remediation

- fix: @modelcontextprotocol/sdk (npm): GitHub reports patched versions 1.32.0. Check the advisory for the affected release branch. (source: GitHub GHSA-6prh-2h8m-c8cw) — https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-6prh-2h8m-c8cw
- fix: @modelcontextprotocol/client (npm): GitHub reports patched versions 2.3.0. Check the advisory for the affected release branch. (source: GitHub GHSA-6prh-2h8m-c8cw) — https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-6prh-2h8m-c8cw
- fix: @modelcontextprotocol/sdk (npm): OSV reports a fixed version 1.32.0. Check the advisory for supported release branches. (source: OSV GHSA-6prh-2h8m-c8cw) — https://github.com/advisories/GHSA-6prh-2h8m-c8cw
- fix: @modelcontextprotocol/client (npm): OSV reports a fixed version 2.3.0. Check the advisory for supported release branches. (source: OSV GHSA-6prh-2h8m-c8cw) — https://github.com/advisories/GHSA-6prh-2h8m-c8cw

## Affected products and versions

- modelcontextprotocol / typescript-sdk: < 1.32.0 (affected). Source: CNA: GitHub_M
- @modelcontextprotocol / sdk: < 1.32.0 (affected). Source: CNA: GitHub_M
- @modelcontextprotocol / client: >= 2.0.0, < 2.3.0 (affected). Source: CNA: GitHub_M
-  / @modelcontextprotocol/sdk (@modelcontextprotocol/sdk): < 1.32.0 (affected, GitHub advisory range). Source: GitHub GHSA-6prh-2h8m-c8cw
-  / @modelcontextprotocol/client (@modelcontextprotocol/client): >= 2.0.0, < 2.3.0 (affected, GitHub advisory range). Source: GitHub GHSA-6prh-2h8m-c8cw
-  / @modelcontextprotocol/sdk (@modelcontextprotocol/sdk): ≥ 0; < 1.32.0 (affected, semver); OSV events: introduced 0; fixed 1.32.0. Source: OSV GHSA-6prh-2h8m-c8cw
-  / @modelcontextprotocol/client (@modelcontextprotocol/client): ≥ 2.0.0; < 2.3.0 (affected, semver); OSV events: introduced 2.0.0; fixed 2.3.0. Source: OSV GHSA-6prh-2h8m-c8cw

## Severity and prioritization

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N; source: CNA: GitHub_M

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: 0.40% as of 2026-11-09; percentile 35.01%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-200

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-6prh-2h8m-c8cw (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/modelcontextprotocol/typescript-sdk/pull/2901 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/modelcontextprotocol/typescript-sdk/pull/2902 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/modelcontextprotocol/typescript-sdk/commit/30bfe5139f4b0825c90cd725f9a7e3f9af5e120d (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/modelcontextprotocol/typescript-sdk/commit/433eb413dc305ebeb93b8ebcde0095a8fc0d5fa0 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/1.32.0 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontextprotocol/server@2.3.0 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/modelcontextprotocol/typescript-sdk/commit/30bfe5139f4b0825c90cd725f9a7e3f9af5e120d (security-advisories@github.com)

- https://github.com/modelcontextprotocol/typescript-sdk/commit/433eb413dc305ebeb93b8ebcde0095a8fc0d5fa0 (security-advisories@github.com)

- https://github.com/modelcontextprotocol/typescript-sdk/pull/2901 (security-advisories@github.com)

- https://github.com/modelcontextprotocol/typescript-sdk/pull/2902 (security-advisories@github.com)

- https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/1.32.0 (security-advisories@github.com)

- https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontextprotocol/server@2.3.0 (security-advisories@github.com)

- https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-6prh-2h8m-c8cw (security-advisories@github.com)

- https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-6prh-2h8m-c8cw (GitHub Security Advisories; advisory)

- https://github.com/advisories/GHSA-6prh-2h8m-c8cw (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-6prh-2h8m-c8cw (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-111769; retrieved 2026-11-09; source updated 2026-11-09

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-111769; retrieved 2026-11-06; source updated 2026-11-05

- GitHub Security Advisories: https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-6prh-2h8m-c8cw; retrieved 2026-11-07; source updated 2026-10-19

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-6prh-2h8m-c8cw; retrieved 2026-11-05; source updated 2026-10-20

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-111769; retrieved 2026-11-09; source updated Not reported

Revision: 79983978f16d79e41efcd242b564be5d977baf270bf150986126aa514ee336f0

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