EUVD-2026-50501

MCP Ruby SDK: Ruby SSE Session Poisoning...

MCP Ruby SDK: Ruby SSE Session Poisoning

Summary Vulnerability: Missing Session Ownership Validation in the Ruby MCP SDK's Streamable and SSE HTTP transport implementation. Any attacker with a stolen session ID can execute tools with the victim's session. This is a silent attack - the victim's session is compromised and being used for...

MCP Ruby SDK: Unbounded JSON-RPC request body causes uncontrolled memory allocation in StreamableHTTPTransport

Summary An unauthenticated remote attacker can force any MCP Ruby SDK server using MCP::Server::Transports::StreamableHTTPTransport to allocate gigabytes of memory by sending a single oversized JSON-RPC POST. The transport reads the entire HTTP body into a Ruby String and parses it with...

EUVD-2026-50502

MCP Ruby SDK: Unbounded JSON-RPC request body causes uncontrolled memory allocation in StreamableHTTPTransport...

EUVD-2026-50498

MCP Ruby SDK: Unbounded session retention in StreamableHTTPTransport allows memory exhaustion via initialize flood...

GHSA-7683-3W9X-CH42 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...

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...

EUVD-2026-50489

MCP Ruby SDK: Streamable HTTP transport lacks DNS-rebinding Host/Origin protection...

CLEANSTART-2026-ZB89546 Security fixes in ruby-fluentd-1.19 1.19.2-r3

Package ruby-fluentd-1.19 version 1.19.2-r3 fixes 9 vulnerabilities: ghsa-h8w8-99g7-qmvj, ghsa-6wx8-w4f5-wwcr, ghsa-wv3x-4vxv-whpp, CVE-2026-54904, CVE-2026-54905...

Low: Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

An update for Red Hat Hardened Images RPMs is now available. This update includes the following RPMs: ruby3.4: ruby3.4-3.4.10-31.5.hum1 aarch64, x8664 ruby3.4-bundled-gems-3.4.10-31.5.hum1 aarch64, x8664 ruby3.4-default-gems-3.4.10-31.5.hum1 noarch ruby3.4-devel-3.4.10-31.5.hum1 aarch64, x8664...

json: Ruby JSON: Denial of service via heap buffer overflow with oversized streamed objects

A flaw was found in Ruby JSON. A remote attacker could exploit a heap buffer overflow vulnerability by providing an oversized streamed object containing a specially crafted string. This could lead to a reliable process crash, resulting in a denial of service DoS for the affected system...

Debian dla-4706 : ruby-rack - security update

The remote Debian 11 / 12 host has a package installed that is affected by multiple vulnerabilities as referenced in the dla-4706 advisory. - ------------------------------------------------------------------------- Debian LTS Advisory DLA-4706-1 [email protected]...

Linux Distros Unpatched Vulnerability : CVE-2026-54522

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - MessagePack for Ruby is an implementation of the MessagePack binary serialization format. Prior to 1.8.2, MessagePack::Bufferclear in ext/msgpack/buffer.c leave...

CVE-2026-54522: Use After Free

MessagePack for Ruby is an implementation of the MessagePack binary serialization format. Prior to 1.8.2, MessagePack::Bufferclear in ext/msgpack/buffer.c leaves rmemlast, rmemend, and rmemowner stale after msgpackbuffershiftchunk returns an rmem page to the shared pool, allowing a subsequent...

Exploit for CVE-2026-66066

🚨 CVE-2026-66066 — KindaRails2Shell Pre-Authenticatio...

CVE-2026-67431

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 bind a session ID to a session owner, allowing an attacker with a stolen session ID to send tools/call requests that...

CVE-2026-67432

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...

CVE-2026-67430

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 proces...

CVE-2026-63118

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 validate the HTTP Host or Origin request headers, which allows a malicious browser page to use DNS rebinding to reach a...