CVE-2026-67430: CWE-401: Missing Release of Memory after Effective Lifetime in modelcontextprotocol ruby-sdk
CVE-2026-67430 is a medium severity vulnerability in the MCP Ruby SDK prior to version 0.23.0. The issue involves the MCP::Server::Transports::StreamableHTTPTransport component not expiring sessions by default, causing unbounded retention of ServerSession objects. This can lead to memory exhaustion in the process due to repeated initialize requests. The vulnerability is fixed in version 0.23.0.
AI Analysis
Technical Summary
The MCP Ruby SDK (modelcontextprotocol ruby-sdk) versions before 0.23.0 contain a memory management flaw where sessions are not expired by default in the MCP::Server::Transports::StreamableHTTPTransport module. This results in repeated initialization requests accumulating ServerSession objects indefinitely, which can exhaust process memory. The issue corresponds to CWE-401 (Missing Release of Memory after Effective Lifetime) and CWE-770 (Use of Improperly Initialized Resource). The vulnerability has a CVSS 3.1 base score of 5.3 (medium severity) with no confidentiality or integrity impact but with availability impact due to potential memory exhaustion. The problem is resolved in version 0.23.0.
Potential Impact
The vulnerability can cause a denial of service condition by exhausting process memory through unbounded retention of session objects. There is no direct impact on confidentiality or integrity. The availability of the affected service may be degraded or interrupted due to memory exhaustion.
Mitigation Recommendations
Upgrade to MCP Ruby SDK version 0.23.0 or later, where the issue is fixed by expiring sessions properly by default. No other mitigation is indicated or required.
CVE-2026-67430: CWE-401: Missing Release of Memory after Effective Lifetime in modelcontextprotocol ruby-sdk
Description
CVE-2026-67430 is a medium severity vulnerability in the MCP Ruby SDK prior to version 0.23.0. The issue involves the MCP::Server::Transports::StreamableHTTPTransport component not expiring sessions by default, causing unbounded retention of ServerSession objects. This can lead to memory exhaustion in the process due to repeated initialize requests. The vulnerability is fixed in version 0.23.0.
CVSS v3.1
Score 5.3medium
Affected software
modelcontextprotocol
ruby-sdk
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The MCP Ruby SDK (modelcontextprotocol ruby-sdk) versions before 0.23.0 contain a memory management flaw where sessions are not expired by default in the MCP::Server::Transports::StreamableHTTPTransport module. This results in repeated initialization requests accumulating ServerSession objects indefinitely, which can exhaust process memory. The issue corresponds to CWE-401 (Missing Release of Memory after Effective Lifetime) and CWE-770 (Use of Improperly Initialized Resource). The vulnerability has a CVSS 3.1 base score of 5.3 (medium severity) with no confidentiality or integrity impact but with availability impact due to potential memory exhaustion. The problem is resolved in version 0.23.0.
Potential Impact
The vulnerability can cause a denial of service condition by exhausting process memory through unbounded retention of session objects. There is no direct impact on confidentiality or integrity. The availability of the affected service may be degraded or interrupted due to memory exhaustion.
Mitigation Recommendations
Upgrade to MCP Ruby SDK version 0.23.0 or later, where the issue is fixed by expiring sessions properly by default. No other mitigation is indicated or required.
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: 6a6a53159c2644c7f8f0f107
Added to database: 07/29/2026, 19:23:01 UTC
Last enriched: 08/06/2026, 17:48:19 UTC
Last updated: 09/11/2026, 22:06:34 UTC
Views: 80
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