# CVE-2026-76893: tsParticles MCP server HTTP session state reuse denial of service

Source: https://junglewise.ai/threats/cve-2026-76893-tsparticles-is-a-typescript-library-for-creating-highly  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-04. Updated: 2026-11-04  
License: CC BY 4.0 with a link back

CVE-2026-76893 · Severity: medium · CVSS 4 · Published 2026-11-04

tsParticles is a TypeScript library for creating particle animations that includes an HTTP-based MCP (Model Context Protocol) server. The MCP server reuses shared transport state across clients, allowing an unauthenticated first client to claim the initialization state and block subsequent clients from establishing sessions until the server restarts. While the first client's session remains functional, legitimate users experience denial of service.

Technologies: [@tsparticles/mcp-server (npm)](https://junglewise.ai/threats/technologies/npm-tsparticles-mcp-server), [tsParticles @Tsparticles/Mcp-Server](https://junglewise.ai/threats/technologies/tsparticles-mcp-server). Vendors: [npm](https://junglewise.ai/threats/vendors/npm), [tsParticles](https://junglewise.ai/threats/vendors/tsparticles).

## Quick answers

**Is CVE-2026-76893 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-76893 being exploited in the wild.

**How severe is CVE-2026-76893?** Medium severity, with a CVSS score of 4, published 4 November 2026.

**Which products and versions are affected?** @tsparticles/mcp-server (npm) < 4.3.2, SEMVER:introduced=0,fixed=4.3.2; tsParticles @Tsparticles/Mcp-Server prior to 4.3.2.

**Is there a fix for CVE-2026-76893?** Yes. @tsparticles/mcp-server (npm): upgrade to 4.3.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-76893 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-76893?** Check whether you run @tsparticles/mcp-server (npm) or tsParticles @Tsparticles/Mcp-Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- @tsparticles/mcp-server (npm): upgrade to 4.3.2 or later

  ```sh
  npm install @tsparticles/mcp-server@4.3.2
  ```


## Technical details

The HTTP mode of @tsparticles/mcp-server uses a single stateful StreamableHTTPServerTransport for all clients without session isolation. An unauthenticated client sending the first initialize request without an mcp-session-id header claims the shared transport state, causing the server to return "Server already initialized" to all subsequent clients. This is a session management flaw that allows unauthenticated denial of service via network access to the HTTP endpoint; the fix in 4.3.2 implements per-session transport isolation and proper authentication.

## Affected products

- tsParticles @tsparticles/mcp-server prior to 4.3.2

## Identifiers

- CVE-2026-76893
- GHSA-h7c4-q426-7jh9

## Timeline

- 2026-11-04: disclosed
- 2026-07-10: patched: Version 4.3.2 released with per-session HTTP transport and authentication controls

## References

- [https://github.com/tsparticles/tsparticles/commit/d3b5672bd61bb847abfa21193c34eabf7aba6896](https://github.com/tsparticles/tsparticles/commit/d3b5672bd61bb847abfa21193c34eabf7aba6896)
- [https://github.com/tsparticles/tsparticles/pull/5888](https://github.com/tsparticles/tsparticles/pull/5888)

## Related threats

- [tsParticles MCP server denial of service via malformed JSON](https://junglewise.ai/threats/cve-2026-76892-tsparticles-is-a-typescript-library-for-creating-highly)
- [tsParticles MCP server denial of service via unbounded buffer allocation](https://junglewise.ai/threats/cve-2026-63655-tsparticles-is-a-typescript-library-for-creating-highly)