{"id":"CVE-2026-76893","title":"tsParticles: A single anonymous MCP session can monopolize HTTP mode and deny new clients","summary":"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 cli…","severity":"medium","cvss":6.9,"cvssVector":"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","cvssSource":"cna","cwe":["CWE-400"],"vendor":"tsparticles","product":"tsparticles","affected":["tsparticles < 4.3.2","mcp-server < 4.3.2"],"ssvc":{"exploitation":"poc","automatable":"yes","technicalImpact":"partial","timestamp":"2026-11-05T20:20:28.208419Z"},"exploitAvailable":true,"published":"2026-11-04","updated":"2026-11-05","sourceUpdated":"2026-11-05T20:20:55.808Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-76893","references":[{"url":"https://github.com/tsparticles/tsparticles/security/advisories/GHSA-h7c4-q426-7jh9","label":"https://github.com/tsparticles/tsparticles/security/advisories/GHSA-h7c4-q426-7jh9"},{"url":"https://github.com/tsparticles/tsparticles/pull/5888","label":"https://github.com/tsparticles/tsparticles/pull/5888"},{"url":"https://github.com/tsparticles/tsparticles/commit/d3b5672bd61bb847abfa21193c34eabf7aba6896","label":"https://github.com/tsparticles/tsparticles/commit/d3b5672bd61bb847abfa21193c34eabf7aba6896"}],"tags":["cve.org","exploit-available"],"epss":0.00291,"epssPercentile":0.21845,"ingestedAt":"2026-11-05T22:38:31.768Z","slug":"CVE-2026-76893","body":"## Overview\n\ntsParticles 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.\n\n## Affected\n\n- `tsparticles < 4.3.2`\n- `mcp-server < 4.3.2`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":50,"depthScoreParts":{"impact":38,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[]}