{"id":"CVE-2026-67432","summary":"MCP Ruby SDK: Unbounded JSON-RPC request body causes uncontrolled memory allocation in StreamableHTTPTransport","details":"MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem reads and parses an entire JSON-RPC POST body without a size limit, allowing an unauthenticated remote attacker to exhaust process memory. This issue is fixed in version 0.23.0.","aliases":["GHSA-h669-8m4g-r2hc"],"modified":"2026-08-12T03:51:29.508752965Z","published":"2026-07-29T19:17:46.518Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-770"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/67xxx/CVE-2026-67432.json"},"references":[{"type":"WEB","url":"https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.23.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/67xxx/CVE-2026-67432.json"},{"type":"ADVISORY","url":"https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-h669-8m4g-r2hc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-67432"},{"type":"FIX","url":"https://github.com/modelcontextprotocol/ruby-sdk/commit/772e0cb1f9db69312006926eee59a7287ad50166"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/modelcontextprotocol/ruby-sdk","events":[{"introduced":"0"},{"fixed":"772e0cb1f9db69312006926eee59a7287ad50166"},{"fixed":"95feef2dcfba25d92a8963d14b7a3b279122f36f"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"0"},{"fixed":"0.23.0"}]}}],"versions":["v0.22.0","v0.21.0","v0.20.0","v0.19.0","v0.18.0","v0.17.0","v0.16.0","v0.15.0","v0.14.0","v0.13.0","v0.12.0","v0.11.0","v0.10.0","v0.9.2","v0.9.1","v0.8.0","v0.9.0","v0.7.1","v0.7.0","v0.6.0","v0.5.0","v0.4.0","v0.3.0","v0.2.0","v0.1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-67432.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}