Tracking: CVE-2026-111767
Severity: High
Who is affected
@modelcontextprotocol/sdk from 1.24.0 through 1.31.0, when an HTTP server shares one experimental taskStore across clients. The advisory says the 2.x SDK is not affected by this finding.
How the attack works
Tasks are not consistently bound to the session that created them. Another client using the shared store can list tasks, read their results, or cancel them. The server's shared storage therefore crosses what callers expect to be a session boundary.
The affected feature is experimental. A server that does not configure taskStore does not have this particular shared-task exposure.
What to do
- Upgrade the 1.x SDK to 1.32.0 or later and redeploy affected servers.
- Remove
taskStoreif tasks are unnecessary. Until upgraded, isolate stores by session instead of sharing one across unrelated clients. - Review task listings, result access, and cancellations across clients. Account for the fix's session binding: a new session cannot automatically resume access to tasks owned by an old session.
Scope and limits
The experimental task feature is deprecated in favor of the newer extension. Check compatibility when migrating rather than assuming a drop-in change.