Report · AWS Security BulletinsAbout CVE-2026-18655Published 3 Aug 2026Updated 20 Aug 2026

CVE-2026-18655: AWS Labs Amazon MQ MCP Server · Broker Credential and OAuth Token Disclosure

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Authoritative record:CVE-2026-18655· Medium 6.5

Not known to be exploited · CVSS 6.5 Medium · patch available : update amazon-mq-mcp-server when convenient.

Data as of 5 Nov 2026, 00:01 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 36% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available

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

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

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 3 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
AWSamazon-mq-mcp-server	Affected <=2.0.23	Fixed in–

AI-suggested

An official fix is available in awslabs.amazon-mq-mcp-server version 2.0.24. Users should upgrade to this version promptly and rotate any broker credentials that may have been exposed. As a temporary mitigation before upgrading, disable auto-approve for the rabbimq_broker_initialize_connection and rabbimq_broker_initialize_connection_with_oauth tools to require manual verification of broker hostnames, rejecting any that do not match the expected Amazon MQ endpoint pattern.

Description

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.

Impact

A remote unauthenticated attacker can obtain sensitive RabbitMQ broker credentials or OAuth access tokens by exploiting the improper endpoint restrictions in the affected versions of the Amazon MQ MCP Server. This could lead to unauthorized access to Amazon MQ brokers and potentially compromise message broker operations or data confidentiality. The impact is significant because it involves credential and token disclosure without authentication.

Summary

AWS Labs Amazon MQ MCP Server (awslabs.amazon-mq-mcp-server) before version 2.0.24 contains an improper restriction of intended endpoints vulnerability in its RabbitMQ broker connection tools. This flaw allows a remote unauthenticated actor to exploit crafted broker hostnames introduced in the MCP client context to capture Amazon MQ RabbitMQ broker credentials or OAuth access tokens sent to attacker-controlled endpoints. The vulnerability affects all versions up to and including 2.0.23. AWS has addressed this issue in version 2.0.24 and recommends upgrading and rotating broker credentials. A temporary workaround is to disable auto-approve for the rabbimq_broker_initialize_connection and rabbimq_broker_initialize_connection_with_oauth tools to enforce manual inspection of broker hostnames.

References

aws.amazon.com/security/security-bulletins/rss/2026-070-aws/ (opens in a new tab)

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