CVE-2026-111767: MCP TypeScript SDK Experimental Tasks Were Not Tied Vulnerability

HIGH
Advisory Identifier: GHSA-22jm-h49p-29qw
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CVSS 8.6
CWE-639 CWE-862
Published
Advisory Summary

CVE-2026-111767 is a HIGH (CVSS 8.6) experimental tasks were not tied vulnerability (CWE-639: Authorization Bypass Through User-Controlled Key) affecting MCP TypeScript SDK libraries in the npm ecosystem. The issue involves experimental tasks were not tied to the session that created them. Remediation is available by upgrading affected packages to version 1.32.0.

CVE-2026-111767 at a Glance

CVE Identifier CVE-2026-111767
GHSA Identifier GHSA-22jm-h49p-29qw
Severity HIGH
CVSS v3.1 Base Score 8.6
CWE Classification CWE-639: Authorization Bypass Through User-Controlled Key
Affected Product MCP TypeScript SDK
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 8.6

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity Low (I:L)
Availability Low (A:L)

How to Fix CVE-2026-111767

To remediate this vulnerability, upgrade all affected MCP TypeScript SDK dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

@modelcontextprotocol/sdk fixed: 1.32.0 
npm install @modelcontextprotocol/sdk@1.32.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls @modelcontextprotocol/sdk

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-111767, inspect your project dependencies using npm:

npm ls @modelcontextprotocol/sdk

Analyze the terminal output to locate any version of MCP TypeScript SDK in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.32.0), your application is affected.

Note: The npm ls @modelcontextprotocol/sdk command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-639: Authorization Bypass Through User-Controlled Key, where the system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. In MCP TypeScript SDK, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary In affected versions, the experimental tasks feature (`taskStore`) did not check which session created a task. Clients sharing one `InMemoryTaskStore` could list, read and cancel each other's tasks. Experimental tasks are deprecated. The 2026-07-28 specification replaced them with a redesigned extension. The best course of action is to stop using them. ### Am I affected? Only if your HTTP server passes `taskStore` to `McpServer` or `Server`. If `grep -ri taskstore --exclude-dir=node_modules .` finds nothing, you are not affected. Affected versions: `@modelcontextprotocol/sdk` 1.24.0 through 1.31.0. The 2.x packages are not affected. ### Fix Upgrade to `@modelcontextprotocol/sdk` 1.32.0 or later. Each task is now tied to the session that created it, so a client that starts a new session can no longer reach its earlier tasks. If you cannot upgrade yet, remove `taskStore`, or create one `InMemoryTaskStore` per session.

CVE-2026-111767 Affected MCP TypeScript SDK Versions

1 component(s)
Fixed Versions:
1.32.0
Product / Package Ecosystem Affected Versions Fixed Version
@modelcontextprotocol/sdk
npm/@modelcontextprotocol/sdk
npm
≥ 1.24.0
< 1.32.0
1.32.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-22jm-h49p-29qw
MCP TypeScript SDK Source Repository REPOSITORY
https://github.com/modelcontextprotocol/typescript-sdk/pull/2925
Security Fix Commit FIX COMMIT
https://github.com/modelcontextprotocol/typescript-sdk/commit/727075b5bbeb77fbea22041b36b72a73042160fa
MCP TypeScript SDK Source Repository REPOSITORY
https://github.com/modelcontextprotocol/typescript-sdk

Frequently Asked Questions

What is CVE-2026-111767?
CVE-2026-111767 is a security vulnerability in MCP TypeScript SDK involving Experimental tasks were not tied to the session that created them under CWE-639: Authorization Bypass Through User-Controlled Key.
Which MCP TypeScript SDK versions are affected?
Affected versions include releases prior to 1.32.0 across affected packages: @modelcontextprotocol/sdk.
What version fixes CVE-2026-111767?
Upgrading to 1.32.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @modelcontextprotocol/sdk affected?
Yes, @modelcontextprotocol/sdk is affected in releases prior to 1.32.0. Upgrade your dependency to 1.32.0 or later.
What is the CVSS score of CVE-2026-111767?
CVE-2026-111767 has a CVSS v3.1 base score of 8.6 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L.
What CWE is associated with CVE-2026-111767?
CVE-2026-111767 is classified under CWE-639: Authorization Bypass Through User-Controlled Key (The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.).
How can I check npm dependencies for CVE-2026-111767?
Run the dependency tree command: 'npm ls @modelcontextprotocol/sdk'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-22jm-h49p-29qw",
  "modified" : "2026-10-20T18:26:54Z",
  "published" : "2026-10-20T18:26:54Z",
  "aliases" : [ "CVE-2026-111767" ],
  "summary" : "MCP TypeScript SDK: Experimental tasks were not tied to the session that created them",
  "details" : "### Summary\nIn affected versions, the experimental tasks feature (`taskStore`) did not check which session created a task. Clients sharing one `InMemoryTaskStore` could list, read and cancel each other's tasks.\n\nExperimental tasks are deprecated. The 2026-07-28 specification replaced them with a redesigned extension. The best course of action is to stop using them.\n\n### Am I affected?\nOnly if your HTTP server passes `taskStore` to `McpServer` or `Server`. If `grep -ri taskstore --exclude-dir=node_modules .` finds nothing, you are not affected.\n\nAffected versions: `@modelcontextprotocol/sdk` 1.24.0 through 1.31.0. The 2.x packages are not affected.\n\n### Fix\nUpgrade to `@modelcontextprotocol/sdk` 1.32.0 or later. Each task is now tied to the session that created it, so a client that starts a new session can no longer reach its earlier tasks.\n\nIf you cannot upgrade yet, remove `taskStore`, or create one `InMemoryTaskStore` per session.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@modelcontextprotocol/sdk"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.24.0"
      }, {
        "fixed" : "1.32.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-22jm-h49p-29qw"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/modelcontextprotocol/typescript-sdk/pull/2925"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/modelcontextprotocol/typescript-sdk/commit/727075b5bbeb77fbea22041b36b72a73042160fa"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/modelcontextprotocol/typescript-sdk"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-639", "CWE-862" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-20T18:26:54Z",
    "nvd_published_at" : null
  }
}