CVE-2026-63119

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Source
https://cve.org/CVERecord?id=CVE-2026-63119
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63119.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-63119
Aliases
Published
2026-07-29T19:12:07Z
Modified
2026-10-28T02:31:14Z
Severity
  • 6.2 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
MCP Ruby SDK: Unbounded line buffer in stdio transports leads to memory exhaustion (DoS)
Details

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.

Database specific 
{
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-400",
        "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63119.json"
}
References

Affected packages

Git / github.com/modelcontextprotocol/ruby-sdk

Affected ranges

Type
GIT
Repo
https://github.com/modelcontextprotocol/ruby-sdk
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
95feef2dcfba25d92a8963d14b7a3b279122f36f
Fixed
267b8fa6285453525c81ce43db6b7dcd7a8a8c2f
Database specific
Show details 
{
    "extracted_events": [
        {
            "range": [
                {
                    "introduced": "0"
                },
                {
                    "fixed": "0.23.0"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StringRangeExpression"
        },
        {
            "range": [
                {
                    "fixed": "267b8fa6285453525c81ce43db6b7dcd7a8a8c2f"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "original_tag": "v0.23.0",
            "range": [
                {
                    "fixed": "95feef2dcfba25d92a8963d14b7a3b279122f36f"
                }
            ],
            "source": "REFERENCES_TAG"
        }
    ]
}

Affected versions

v0.*
v0.1.0
v0.10.0
v0.11.0
v0.12.0
v0.13.0
v0.14.0
v0.15.0
v0.16.0
v0.17.0
v0.18.0
v0.19.0
v0.2.0
v0.20.0
v0.21.0
v0.22.0
v0.3.0
v0.4.0
v0.5.0
v0.6.0
v0.7.0
v0.7.1
v0.8.0
v0.9.0
v0.9.1
v0.9.2

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63119.json"