CVE-2026-63119
Published:July 29, 2026
Updated:August 04, 2026
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.
Affected Packages
https://github.com/modelcontextprotocol/ruby-sdk.git (GITHUB):
Affected version(s) >=v0.1.0 <v0.23.0Fix Suggestion:
Update to version v0.23.0mcp (RUBY):
Affected version(s) >=0.0.1 <0.23.0Fix Suggestion:
Update to version 0.23.0Related Resources (6)
Do you need more information?
Contact UsCVSS v4
Base Score:
6.9
Attack Vector
LOCAL
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.2
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
EPSS
Base Score:
0.13