MEDIUMCVSS 6.2EPSS 0.1%

CVE-2026-63119

CVE-2026-63119 updated by NVD

Published: 2026-07-30
Modified: 2026-07-31
EPSS percentile: 3%
Sources: github-advisory, nvd

Summary

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

Ecosystem	Package	Affected versions	Fixed versions
RubyGems	mcp	—	0.23.0

Remediation: Upgrade to 0.23.0 or later.

References

https://nvd.nist.gov/vuln/detail/CVE-2026-63119

Includes data from the GitHub Advisory Database, licensed under CC-BY 4.0.

Includes data from the National Vulnerability Database (NIST). NVD data is in the public domain; this page is not endorsed by NIST.

CVE® is a registered trademark of The MITRE Corporation. CVE content reproduced under the CVE Terms of Use; copyright designation © MITRE.

EPSS scores provided by the FIRST.org Exploit Prediction Scoring System.