modelcontextprotocol ruby-sdk up to 0.22.x StdioTransport IO#gets allocation of resources

CVSS Meta Temp Score
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CTI Interest Score
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4.1$0-$5k0.95

Summaryinfo

A vulnerability classified as problematic has been found in modelcontextprotocol ruby-sdk up to 0.22.x. This affects the function IO#gets of the component StdioTransport. This manipulation causes allocation of resources. This vulnerability is handled as CVE-2026-63119. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in modelcontextprotocol ruby-sdk up to 0.22.x. It has been declared as problematic. Affected by this vulnerability is the function IO#gets of the component StdioTransport. The manipulation with an unknown input leads to a allocation of resources vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-63119 since 07/15/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 0.23.0 eliminates this vulnerability.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

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Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.3
VulDB Meta Temp Score: 4.1

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
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

07/15/2026 CVE reserved
07/29/2026 +14 days Advisory disclosed
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-2026-63119 (🔒)
GCVE (CVE): GCVE-0-2026-63119
GCVE (VulDB): GCVE-100-384271

Entryinfo

Created: 07/29/2026 22:13
Changes: 07/29/2026 22:13 (57)
Complete: 🔍
Cache ID: 216::103

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