CVE-2026-63119: MCP Ruby SDK: Unbounded line buffer in stdio transports leads to memory exhaustion (DoS)
modelcontextprotocol · ruby-sdk
Affected: modelcontextprotocol ruby-sdk · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 8% of scored CVEs
DescriptionCVE.org
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 products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- modelcontextprotocol · ruby-sdk< 0.23.0
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- modelcontextprotocol
- Published
- July 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-63119 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.