CVE-2026-63119: CWE-400: Uncontrolled Resource Consumption in modelcontextprotocol ruby-sdk
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.
AI Analysis
Technical Summary
The modelcontextprotocol Ruby SDK versions before 0.23.0 contain an uncontrolled resource consumption vulnerability (CWE-400) due to the use of IO#gets without a byte limit in MCP::Server::Transports::StdioTransport and MCP::Client::Stdio. This allows a remote peer to send data without a newline character, causing the process to consume excessive memory and potentially crash. The issue is addressed in version 0.23.0 of the SDK.
Potential Impact
An attacker who can send data to the affected components can cause the process to consume excessive memory, leading to denial of service conditions. There is no impact on confidentiality or integrity reported. The CVSS v3.1 base score is 6.2 (medium), with the vector indicating local attack vector, low attack complexity, no privileges required, no user interaction, unchanged scope, no confidentiality or integrity impact, and high availability impact.
Mitigation Recommendations
Upgrade to version 0.23.0 or later of the modelcontextprotocol Ruby SDK, where this vulnerability is fixed. No other official remediation or temporary fixes are indicated. Patch status is not explicitly stated as 'patchAvailable' but the fix is confirmed in version 0.23.0.
CVE-2026-63119: CWE-400: Uncontrolled Resource Consumption in modelcontextprotocol ruby-sdk
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.
CVSS v3.1
Score 6.2medium
Affected software
modelcontextprotocol
ruby-sdk
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The modelcontextprotocol Ruby SDK versions before 0.23.0 contain an uncontrolled resource consumption vulnerability (CWE-400) due to the use of IO#gets without a byte limit in MCP::Server::Transports::StdioTransport and MCP::Client::Stdio. This allows a remote peer to send data without a newline character, causing the process to consume excessive memory and potentially crash. The issue is addressed in version 0.23.0 of the SDK.
Potential Impact
An attacker who can send data to the affected components can cause the process to consume excessive memory, leading to denial of service conditions. There is no impact on confidentiality or integrity reported. The CVSS v3.1 base score is 6.2 (medium), with the vector indicating local attack vector, low attack complexity, no privileges required, no user interaction, unchanged scope, no confidentiality or integrity impact, and high availability impact.
Mitigation Recommendations
Upgrade to version 0.23.0 or later of the modelcontextprotocol Ruby SDK, where this vulnerability is fixed. No other official remediation or temporary fixes are indicated. Patch status is not explicitly stated as 'patchAvailable' but the fix is confirmed in version 0.23.0.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-07-15T16:54:55.816Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6a6a53159c2644c7f8f0f102
Added to database: 07/29/2026, 19:23:01 UTC
Last enriched: 07/29/2026, 19:37:39 UTC
Last updated: 09/12/2026, 22:01:35 UTC
Views: 68
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