{"cve":"CVE-2026-63119","nvd":{"published":"2026-07-29T20:17:10.790","modified":"2026-10-24T13:10:00.147","status":"Deferred","description":"MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StdioTransport and MCP::Client::Stdio in the mcp gem use IO#gets without a byte limit, allowing a peer that sends data without a newline to exhaust process memory. This issue is fixed in version 0.23.0.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":6.2},"cwes":["CWE-400","CWE-770"],"references":["https://github.com/modelcontextprotocol/ruby-sdk/commit/267b8fa6285453525c81ce43db6b7dcd7a8a8c2f","https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.23.0","https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-7683-3w9x-ch42","https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-7683-3w9x-ch42"],"products":[],"source":"nvd","synced_at":"2026-10-24T16:53:27.712498749+00:00"},"epss":{"cve":"CVE-2026-63119","score":0.00188,"percentile":0.08317,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-7683-3w9x-ch42","url":"https://osv.dev/vulnerability/GHSA-7683-3w9x-ch42","summary":"MCP Ruby SDK: Unbounded line buffer in stdio transports leads to memory exhaustion (DoS)","modified":"2026-07-30T14:45:28.029711933Z","packages":[{"ecosystem":"RubyGems","name":"mcp","purl":"pkg:gem/mcp","ranges":["<0.23.0"],"fixed":["0.23.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}