CVE-2026-67432: CWE-770: Allocation of Resources Without Limits or Throttling 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::StreamableHTTPTransport in the mcp gem reads and parses an entire JSON-RPC POST body without a size limit, allowing an unauthenticated remote attacker to exhaust process memory. This issue is fixed in version 0.23.0.
AI Analysis
Technical Summary
CVE-2026-67432 is a resource exhaustion vulnerability classified under CWE-770 (Allocation of Resources Without Limits or Throttling) in the MCP Ruby SDK. Specifically, versions before 0.23.0 of the mcp gem's MCP::Server::Transports::StreamableHTTPTransport component do not impose size limits on JSON-RPC POST bodies. This allows unauthenticated remote attackers to send very large payloads that cause the server process to consume excessive memory, potentially leading to denial of service. The vulnerability has a CVSS 3.1 score of 7.5 (high severity) with network attack vector, low attack complexity, no privileges required, no user interaction, and impacts availability only. The issue is resolved in version 0.23.0.
Potential Impact
An unauthenticated remote attacker can cause denial of service by exhausting the process memory of the MCP Ruby SDK server due to unbounded JSON-RPC POST body parsing. This impacts availability but does not affect confidentiality or integrity.
Mitigation Recommendations
Upgrade to MCP Ruby SDK version 0.23.0 or later, where this vulnerability is fixed by imposing size limits on JSON-RPC POST bodies. Patch status is confirmed by the vendor advisory stating the fix in version 0.23.0. Until upgraded, consider implementing external request size limits or filtering to mitigate potential attacks.
CVE-2026-67432: CWE-770: Allocation of Resources Without Limits or Throttling 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::StreamableHTTPTransport in the mcp gem reads and parses an entire JSON-RPC POST body without a size limit, allowing an unauthenticated remote attacker to exhaust process memory. This issue is fixed in version 0.23.0.
CVSS v3.1
Score 7.5high
Affected software
modelcontextprotocol
ruby-sdk
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-67432 is a resource exhaustion vulnerability classified under CWE-770 (Allocation of Resources Without Limits or Throttling) in the MCP Ruby SDK. Specifically, versions before 0.23.0 of the mcp gem's MCP::Server::Transports::StreamableHTTPTransport component do not impose size limits on JSON-RPC POST bodies. This allows unauthenticated remote attackers to send very large payloads that cause the server process to consume excessive memory, potentially leading to denial of service. The vulnerability has a CVSS 3.1 score of 7.5 (high severity) with network attack vector, low attack complexity, no privileges required, no user interaction, and impacts availability only. The issue is resolved in version 0.23.0.
Potential Impact
An unauthenticated remote attacker can cause denial of service by exhausting the process memory of the MCP Ruby SDK server due to unbounded JSON-RPC POST body parsing. This impacts availability but does not affect confidentiality or integrity.
Mitigation Recommendations
Upgrade to MCP Ruby SDK version 0.23.0 or later, where this vulnerability is fixed by imposing size limits on JSON-RPC POST bodies. Patch status is confirmed by the vendor advisory stating the fix in version 0.23.0. Until upgraded, consider implementing external request size limits or filtering to mitigate potential attacks.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-07-29T15:07:24.991Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6a6a53159c2644c7f8f0f111
Added to database: 07/29/2026, 19:23:01 UTC
Last enriched: 07/29/2026, 19:36:58 UTC
Last updated: 09/10/2026, 19:59:54 UTC
Views: 90
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