CVE-2026-76893
Received Received - Intake

HTTP State Reuse in tsParticles MCP Server

Publication date: 2026-11-04

Last updated on: 2026-11-04

Assigner: GitHub, Inc.

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.

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Meta Information

Published
2026-11-04
Last Modified
2026-11-04
Generated
2026-11-05
AI Q&A
2026-11-05
EPSS Evaluated
N/A
NVD
CVE-2026-76893

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
tsparticles tsparticles < 4.3.2
@tsparticles mcp-server < 4.3.2

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.

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Executive Summary

The vulnerability in tsParticles' HTTP mode of @tsparticles/mcp-server before version 4.3.2 involves a shared stateful StreamableHTTPServerTransport used for all clients. An unauthenticated client can claim this shared transport by sending an initialize request without an mcp-session-id, causing later clients to receive a 'Server already initialized' error and preventing them from establishing sessions until the process restarts.

Impact Analysis

This vulnerability allows an attacker to disrupt service for legitimate users by preventing them from establishing sessions. The first client's session remains unaffected, but subsequent users cannot connect until the server restarts, leading to denial-of-service conditions for multiple users.

Mitigation Strategies

Upgrade @tsparticles/mcp-server to version 4.3.2 or later to address the stateful transport issue affecting HTTP mode.

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