CVE-2026-76893

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

Published Nov 4, 2026 CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-h7c4-q426-7jh9 tsParticles: A single anonymous MCP session can monopolize HTTP mode and deny new clients
History
Type Values Removed Values Added
First Time appeared Tsparticles
Tsparticles mcp-server
Tsparticles tsparticles
Vendors & Products Tsparticles
Tsparticles mcp-server
Tsparticles tsparticles
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title tsParticles: A single anonymous MCP session can monopolize HTTP mode and deny new clients
Weaknesses CWE-400
References
Metrics cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Nov 5, 2026, 8:20 PM
Reserved
Aug 19, 2026, 10:43 PM
Status
Deferred
Published
Nov 4, 2026, 10:18 PM
Modified
Nov 6, 2026, 9:32 PM