CVE-2026-67430: CWE-401: Missing Release of Memory after Effective Lifetime in modelcontextprotocol ruby-sdk
A memory management vulnerability exists in the MCP Ruby SDK prior to version 0.23.0. Specifically, the StreamableHTTPTransport component does not expire sessions by default, causing unbounded retention of ServerSession objects. This can lead to process memory exhaustion over time. The issue is addressed in version 0.23.0.
AI Analysis
Technical Summary
CVE-2026-67430 is a medium severity vulnerability in the modelcontextprotocol ruby-sdk before version 0.23.0. The MCP::Server::Transports::StreamableHTTPTransport class fails to expire sessions by default, resulting in unbounded accumulation of ServerSession objects when repeated initialize requests occur. This leads to a memory leak (CWE-401) and potential resource exhaustion (CWE-770). The vulnerability has a CVSS 3.1 base score of 5.3, reflecting a network attack vector with low complexity and no required privileges or user interaction, causing availability impact only. The issue is fixed starting from version 0.23.0.
Potential Impact
The vulnerability causes a memory leak in the MCP Ruby SDK server component, which can exhaust process memory due to unexpired sessions accumulating indefinitely. This impacts availability by potentially causing service degradation or crashes. There is no confidentiality or integrity impact reported.
Mitigation Recommendations
Upgrade to MCP Ruby SDK version 0.23.0 or later, where the session expiration issue is fixed. No other mitigation or workaround is indicated. Patch status is confirmed by the vendor advisory stating the fix is included in version 0.23.0.
CVE-2026-67430: CWE-401: Missing Release of Memory after Effective Lifetime in modelcontextprotocol ruby-sdk
Description
A memory management vulnerability exists in the MCP Ruby SDK prior to version 0.23.0. Specifically, the StreamableHTTPTransport component does not expire sessions by default, causing unbounded retention of ServerSession objects. This can lead to process memory exhaustion over time. The issue is addressed in version 0.23.0.
CVSS v3.1
Score 5.3medium
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-67430 is a medium severity vulnerability in the modelcontextprotocol ruby-sdk before version 0.23.0. The MCP::Server::Transports::StreamableHTTPTransport class fails to expire sessions by default, resulting in unbounded accumulation of ServerSession objects when repeated initialize requests occur. This leads to a memory leak (CWE-401) and potential resource exhaustion (CWE-770). The vulnerability has a CVSS 3.1 base score of 5.3, reflecting a network attack vector with low complexity and no required privileges or user interaction, causing availability impact only. The issue is fixed starting from version 0.23.0.
Potential Impact
The vulnerability causes a memory leak in the MCP Ruby SDK server component, which can exhaust process memory due to unexpired sessions accumulating indefinitely. This impacts availability by potentially causing service degradation or crashes. There is no confidentiality or integrity impact reported.
Mitigation Recommendations
Upgrade to MCP Ruby SDK version 0.23.0 or later, where the session expiration issue is fixed. No other mitigation or workaround is indicated. Patch status is confirmed by the vendor advisory stating the fix is included in version 0.23.0.
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
- Remediation Level
- null
Threat ID: 6a6a53159c2644c7f8f0f107
Added to database: 07/29/2026, 19:23:01 UTC
Last enriched: 07/29/2026, 19:37:35 UTC
Last updated: 07/29/2026, 19:37:35 UTC
Views: 4
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