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Medium · 6.9 CVE-2026-76893 EUVD-2026-117156GHSA-h7c4-q426-7jh9

tsParticles: A single anonymous MCP session can monopolize HTTP mode and deny new clients

Published Nov 4, 2026 · Updated Nov 5, 2026 · Assigned by GitHub_M

Description

tsParticles is a TypeScript library for creating highly customizable particle animations. Prior to 4.3.2, the HTTP mode of @tsparticles/mcp-server reuses one stateful StreamableHTTPServerTransport for every client. An unauthenticated client that sends the first initialize request without an mcp-session-id claims the shared transport state, causing later independent clients to receive Server already initialized and preventing them from establishing sessions until the process restarts. The first client's session remains functional. This issue is fixed in version 4.3.2.

Affected products

VendorProductAffectedFixed
tsparticles tsparticles < 4.3.2 —
@tsparticles mcp-server < 4.3.2 —

Affected packages

EcosystemPackageAffectedFixedRecord
npm @tsparticles/mcp-server < 4.3.2 4.3.2 GHSA-h7c4-q426-7jh9

References