modelcontextprotocol ruby-sdk up to 0.22.x StreamableHTTPTransport allocation of resources

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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5.1$0-$5k1.69+

Summaryinfo

A vulnerability classified as problematic was found in modelcontextprotocol ruby-sdk up to 0.22.x. This impacts the function MCP::Server::Transports::StreamableHTTPTransport of the component StreamableHTTPTransport. Such manipulation leads to allocation of resources. This vulnerability is uniquely identified as CVE-2026-67430. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability was found in modelcontextprotocol ruby-sdk up to 0.22.x. It has been rated as problematic. Affected by this issue is the function MCP::Server::Transports::StreamableHTTPTransport of the component StreamableHTTPTransport. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. Impacted is availability. CVE summarizes:

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 does not expire sessions by default, so repeated initialize requests retain unbounded ServerSession objects and can exhaust process memory. This issue is fixed in version 0.23.0.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-67430 since 07/29/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 0.23.0 eliminates this vulnerability.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.1

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Allocation of resources
CWE: CWE-770 / CWE-400 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: ruby-sdk 0.23.0

Timelineinfo

07/29/2026 Advisory disclosed
07/29/2026 +0 days CVE reserved
07/29/2026 +0 days VulDB entry created
07/29/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-67430 (🔒)
GCVE (CVE): GCVE-0-2026-67430
GCVE (VulDB): GCVE-100-384272

Entryinfo

Created: 07/29/2026 22:14
Changes: 07/29/2026 22:14 (57)
Complete: 🔍
Cache ID: 216::103

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