CVE-2026-63118: MCP Ruby SDK: Streamable HTTP transport lacks DNS-rebinding (Host/Origin) protection
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 15% 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::StreamableHTTPTransport in the mcp gem does not validate the HTTP Host or Origin request headers, which allows a malicious browser page to use DNS rebinding to reach a locally running MCP server and invoke exposed tools. 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-2026-63118 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.