---
title: "CVE-2026-104850: MCP TypeScript SDK - Authentication Bypass"
description: "MCP TypeScript SDK <= 1.12.0 and < 1.31.0, 2.x < 2.2.0 contains an OAuth client authorization bypass caused by unbound stored credentials to authorization servers, letting malicious MCP servers receive client OAuth credentials without user interaction, exploit requires untrusted MCP server connection."
url: https://panop.io/threat-heartbeat/CVE-2026-104850/
---

# CVE-2026-104850 MCP TypeScript SDK - Authentication Bypass

MCP TypeScript SDK <= 1.12.0 and < 1.31.0, 2.x < 2.2.0 contains an OAuth client authorization bypass caused by unbound stored credentials to authorization servers, letting malicious MCP servers receive client OAuth credentials without user interaction, exploit requires untrusted MCP server connection.

CVSS base score 7.5 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.18% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-104850)

## Details

Type

Authentication Bypass

Impact

Information Disclosure

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Published

6 October 2026

Updated

15 October 2026

Weakness

[CWE-345](https://cwe.mitre.org/data/definitions/345.html)

## Vendor fix

Upgrade to @modelcontextprotocol/sdk 1.31.0 or @modelcontextprotocol/client 2.2.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-104850](https://nvd.nist.gov/vuln/detail/CVE-2026-104850)
- [https://github.com/modelcontextprotocol/typescript-sdk/commit/edd12e282620ebf770d67316f19cf91d4112a1bd](https://github.com/modelcontextprotocol/typescript-sdk/commit/edd12e282620ebf770d67316f19cf91d4112a1bd)
- [https://github.com/modelcontextprotocol/typescript-sdk/pull/2887](https://github.com/modelcontextprotocol/typescript-sdk/pull/2887)
- [https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/v2.2.0](https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/v2.2.0)
- [https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-6qxp-vccf-f47h](https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-6qxp-vccf-f47h)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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