CVE-2026-111767: MCP TypeScript SDK: Experimental tasks were not tied to the session that created them
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=nodemodules . 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.
Other sources
MCP TypeScript SDK is the official TypeScript SDK for Model Context Protocol servers and clients. From version 1.24.0 to before version 1.32.0, 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. This issue has been patched in version 1.32.0.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
npm/@modelcontextprotocol/sdkto a version that resolves this vulnerability.Fixed in 1.32.0 - Upgrade
Upgrade
@modelcontextprotocol/sdkto a version that resolves this vulnerability.Fixed in 1.32.0 - Configuration
If you cannot upgrade to 1.32.0, remove taskStore, or create one InMemoryTaskStore per session.
MCP TypeScript SDK experimental tasks taskStore = removed or one InMemoryTaskStore per session
Event History
Frequently Asked Questions
Which deployments are exposed to cross-client task access?
Deployments using the experimental tasks feature (taskStore) with a shared InMemoryTaskStore are affected. In that configuration, clients can list, read, and cancel tasks created by other clients.
What access does an attacker need to exploit this issue?
An attacker needs to act as a client sharing the same InMemoryTaskStore as other clients. The issue does not require privileges or user interaction according to the supplied severity vector.
Which SDK versions are affected, and what version fixes the issue?
Affected versions range from 1.24.0 up to, but not including, 1.32.0. The issue is patched in version 1.32.0.