CVE-2026-63119
MCP Ruby SDK: Unbounded line buffer in stdio transports leads to memory exhaustion (DoS)
Description
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.
No summary for this CVE yet.
CVSS Vector Breakdown
Exploitability
AV:LAttack VectorLocal
AC:LAttack ComplexityLow
PR:NPrivileges RequiredNone
UI:NUser InteractionNone
Scope
S:UScopeUnchanged
Impact
C:NConfidentialityNone
I:NIntegrityNone
A:HAvailabilityHigh
Weaknesses
Affected Products
modelcontextprotocol
oss-projectaka model context protocol, mcp
Exploitability
No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.
Attack Graph
Products CVE Techniques Tactics
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MITRE ATT&CK
1 technique Impact
References
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