PT-2026-65889 · Modelcontextprotocol · Ruby-Sdk

CVE-2026-63119 · Published 2026-07-29 · Updated 2026-07-29

Mitre

CVSS v3.1

6.2

Medium

Base vector

AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

Exploit

Fix

Resource Exhaustion

Allocation of Resources Without Limits

Weakness Enumeration

CWE-400

CWE-770

Related Identifiers

CVE-2026-63119

Affected Products

Ruby-Sdk

References · 4

• 🔥 https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-7683-3w9x-ch42 · Exploit
• https://nvd.nist.gov/vuln/detail/CVE-2026-63119 · Security Note
• https://github.com/modelcontextprotocol/ruby-sdk/commit/267b8fa6285453525c81ce43db6b7dcd7a8a8c2f · Note
• https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.23.0 · Note