CVE-2026-16584

Policy bypass via fail-open initialization

Published Jul 23, 2026 · Updated Jul 23, 2026

Security policy bypass in AWS API MCP Server 0.2.13 through 1.3.46 allows attackers to execute policy-denied AWS API operations. The main startup routine catches a get_read_only_operations failure, leaves READ_OPERATIONS_INDEX unset, and call_aws_helper omits check_security_policy when that index is absent. Exploitation requires a configured policy without fail-closed mode and a startup initialization failure; IAM permissions still bound executable operations.

CVSS severity7.3
High
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Security policy bypass in AWS API MCP Server 0.2.13 through 1.3.46 allows attackers to execute policy-denied AWS API operations. The main startup routine catches a get_read_only_operations failure, leaves READ_OPERATIONS_INDEX unset, and call_aws_helper omits check_security_policy when that index is absent. Exploitation requires a configured policy without fail-closed mode and a startup initialization failure; IAM permissions still bound executable operations.

The record

CVE
CVE-2026-16584
Published
Jul 23, 2026
Updated
Jul 23, 2026
Vendor
Amazon Web Services
Product
AWS API MCP Server
Classifications
CWE-455, T1562.001
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.2.13 <1.3.47

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Amazon Web Services · AWS API MCP Serverversion=0.2.13 <1.3.47

Published CVSS scores

7.3Amazon Web ServicesCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
7.0Amazon Web ServicesCVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-455Non-exit on Failed Initialization
T1562.001Impair Defenses: Disable or Modify Tools

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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