EUVD-2026-50500

MCP Ruby SDK: Unbounded line buffer in stdio transports leads to memory exhaustion DoS...

MCP Ruby SDK: Unbounded line buffer in stdio transports leads to memory exhaustion (DoS)

Summary The stdio transports in MCP::Server::Transports::StdioTransport and MCP::Client::Stdio read newline-delimited JSON-RPC frames using IOgets with no limit argument. CRuby's IOgets with no limit reads from the current position until the next separator \n with no upper bound on the returned...

CVE-2026-12940: Improper Neutralization of Special Elements used in an OS Command

IBM Langflow OSS 1.0.0 through 1.10.1 are vulnerable to unauthenticated remote code execution via environment variable injection in the MCP Model Context Protocol stdio launcher. The vulnerability exists in src/lfx/src/lfx/base/mcp/util.py where the DANGEROUSENVVARS blocklist fails to include...

CVE-2026-63119 MCP Ruby SDK: Unbounded line buffer in stdio transports leads to memory exhaustion (DoS)

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 IOgets without a byte limit, allowing a peer that sends data without a newline to exhaust process memory. This...

CVE-2026-63119

The CVE affects the MCP Ruby SDK (mcp gem), specifically MCP::Server::Transports::StdioTransport and MCP::Client::Stdio. The vulnerability arises from using IO#gets without a byte limit, allowing an attacker to send data without a newline and trigger unbounded line buffering, causing memory exhau...

CVE-2026-63119

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 IOgets without a byte limit, allowing a peer that sends data without a newline to exhaust process memory. This...

CVE-2026-63119 MCP Ruby SDK: Unbounded line buffer in stdio transports leads to memory exhaustion (DoS)

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 IOgets without a byte limit, allowing a peer that sends data without a newline to exhaust process memory. This...

CVE-2026-63119 MCP Ruby SDK: Unbounded line buffer in stdio transports leads to memory exhaustion (DoS)

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 IOgets without a byte limit, allowing a peer that sends data without a newline to exhaust process memory. This...

PT-2026-65889

Name of the Vulnerable Software and Affected Versions mcp versions prior to 0.23.0 Description The MCP::Server::Transports::StdioTransport and MCP::Client::Stdio components in the mcp gem use the IOgets function without a byte limit. This allows a peer that sends data without a newline character ...

CVE-2026-63119: Uncontrolled Resource Consumption

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 IOgets without a byte limit, allowing a peer that sends data without a newline to exhaust process memory. This...

LangBot: Authenticated RCE Via MCP Configuration

SummaryAny authenticated user can achieve arbitrary command execution on the LangBot servers through changing the MCP Server Configuration by added an "STDIO" MCP with an arbitrary command. DetailsThe repository uses StdioServerParameters which is based on Anthropic's modelcontextprotocol open...

PYSEC-2026-3473 LangBot: Authenticated RCE Via MCP Configuration

Summary Any authenticated user can achieve arbitrary command execution on the LangBot servers through changing the MCP Server Configuration by added an "STDIO" MCP with an arbitrary command. Details The repository uses StdioServerParameters which is based on Anthropic's modelcontextprotocol open...

Exploit for CVE-2026-30623

mcpshield !Python 3.10+https://img.shields.io/badge/python...

Allocation of Resources Without Limits or Throttling

Overview mcp is a The official Ruby SDK for Model Context Protocol servers and clients Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling in the stdio transports lib/mcp/server/transports/stdiotransport.rb and lib/mcp/client/stdio.rb, which ca...

CVE-2026-30618: Improper Control of Generation of Code

xszyou Fay 4.3.1 contains a remote code execution vulnerability in its MCP STDIO server management and command execution handling. A remote attacker can access the publicly exposed MCP management interface and configure an MCP STDIO server with attacker-controlled commands and parameters, resulti...

CVE-2026-54149

MaxKB is an open-source AI assistant for enterprise. Prior to 2.10.0-lts, MaxKB tool import functionality in apps/tools/serializers/tool.py and MCP referencing mode in apps/application/chatpipeline/step/chatstep/impl/basechatstep.py do not consistently validate MCP transport type, allowing an...

CVE-2026-54149 MaxKB MCP tool import validation bypass allows post-authentication remote code execution

MaxKB is an open-source AI assistant for enterprise. Prior to 2.10.0-lts, MaxKB tool import functionality in apps/tools/serializers/tool.py and MCP referencing mode in apps/application/chatpipeline/step/chatstep/impl/basechatstep.py do not consistently validate MCP transport type, allowing an...

Neo4j Cypher MCP server is vulnerable to DNS rebinding

ImpactDNS rebinding vulnerability in Neo4j Cypher MCP server allows malicious websites to bypass Same-Origin Policy protections and execute unauthorised tool invocations against locally running Neo4j MCP instances. The attack relies on the user being enticed to visit a malicious website and spend...

Unbounded line buffer in stdio transports leads to memory exhaustion (DoS)

Summary The stdio transports in MCP::Server::Transports::StdioTransport and MCP::Client::Stdio read newline-delimited JSON-RPC frames using IOgets with no limit argument. CRuby's IOgets with no limit reads from the current position until the next separator \n with no upper bound on the returned...

PYSEC-2026-559 Upsonic: remote code execution vulnerability in its MCP server/task creation functionality

Upsonic 0.71.6 contains a remote code execution vulnerability in its MCP server/task creation functionality. The application allows users to define MCP tasks with arbitrary command and args values. Although an allowlist exists, certain allowed commands npm, npx accept argument flags that enable...