CVE-2026-67432 | BDVDB-2026-353633 Detail

modelcontextprotocolruby-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.

Impact#

Per CVSS v3.1: confidentiality impact none, integrity impact none, availability impact high. Attack vector: network.

Weaknesses#

CWE-770 Allocation of Resources Without Limits or Throttling

References#

Exploit#

No public exploit known

History#

Version 12026-07-29Record published in the CVE List.

Published

Published: 2026-07-29
Last modified: 2026-07-29

Vendor information

Vendor: modelcontextprotocol
Product: ruby-sdk

All modelcontextprotocol vulnerabilities

Score

7.5 High

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 56.4.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Not classified

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
< 0.23.0
Fixed
Not stated

Scoring System

CVSS v4.0

Not available

CVSS v3.1

7.5 High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Privileges Required	None
User Interaction	None
Scope	Unchanged
Confidentiality	None
Integrity	None
Availability	High

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).