CVE-2026-18655 - Broker Credential and OAuth Token Disclosure in AWS Labs Amazon MQ MCP Server via Prompt Injection

unknownCVE-2026-18655

Bulletin ID: 2026-070-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 08/03/2026 12:00 PM PDT Description: AWS Amazon MQ MCP Server (awslabs.amazon-mq-mcp-server) is a Model Context Protocol server that enables AI assistants to interact with Amazon MQ message brokers. We identified CVE-2026-18655, an improper restriction of intended endpoints in the RabbitMQ broker connection tools of the Amazon MQ MCP Server (awslabs.amazon-mq-mcp-server) before 2.0.24 that may allow a remote unauthenticated actor to obtain Amazon MQ for RabbitMQ broker credentials or OAuth access tokens sent to a crafted endpoint controlled through a broker hostname introduced in the MCP client context. Impacted versions: <= 2.0.23 Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.

Details

Source: AWS Security Bulletins (INTL · vendor-psirt · site)
Severity: unknown
Published: 2026-08-03
Exploitation: Not in CISA KEV at last sync

Original advisory: https://aws.amazon.com/security/security-bulletins/rss/2026-070-aws/

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-186550.25% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 17% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-18655	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

mediumCVE-2026-18655: Improper restriction of intended endpoints in the RabbitMQ broker connection tools of the Amaz…nvd

Recent advisories for - Broker Credential

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

mediumGHSA-8gj2-2cvc-6xx7: Flowise: Unauthenticated Credential Abuse via Text-to-Speech Endpoint Allows Unauthorized…ghsa · 2026-08-04
unknownCVE-2026-70474: Flowise is a drag-and-drop user interface for building customized large language model (LLM) f…nvd · 2026-08-04
highGHSA-wch5-xp77-fxg4: Flowise: Cross-Workspace OAuth2 Credential Metadata Leakghsa · 2026-08-04
mediumGHSA-rwrp-9823-p2xq: Flowise: Incomplete Credential Redaction Exposes Secrets via APIghsa · 2026-08-04
highGHSA-chm3-vqcf-52rx: Flowise: Cross-workspace credential IDOR in openai-assistants-vector-storeghsa · 2026-08-04
unknownCVE-2026-58073: A vulnerability in Veeam Service Provider Console allowing an unauthenticated attacker to impe…nvd · 2026-08-04