CVE-2026-87913
Received Received - Intake

S3 Bucket Ownership Verification Bypass in AWS Security Agent MCP

Publication date: 2026-09-10

Last updated on: 2026-09-10

Assigner: AMZN

Description
A missing S3 bucket ownership verification in the AWS Security Agent MCP server before 0.2.0 version might allow remote attackers to obtain the private source archive of a scanned workspace, including credentials and infrastructure state contained in that archive, via a pre-registered storage bucket whose name is derived from a publicly known account identifier. To remediate this issue, users should upgrade to version 0.2.0. Users should also verify that the scan output bucket in their account is owned by their own account, because upgrading does not release a bucket name that a third party has already registered.

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Meta Information

Published
2026-09-10
Last Modified
2026-09-10
Generated
2026-09-10
AI Q&A
2026-09-10
EPSS Evaluated
N/A
NVD
CVE-2026-87913
EUVD
EUVD-2026-75571

Affected Vendors & Products

Showing 7 associated CPEs
Vendor Product Version / Range
awslabs security-agent-mcp-server 0.1.0
awslabs security-agent-mcp-server 0.1.1
awslabs security-agent-mcp-server 0.1.2
awslabs security-agent-mcp-server 0.1.3
awslabs security-agent-mcp-server 0.1.4
awslabs security-agent-mcp-server 0.1.5
awslabs security-agent-mcp-server 0.2.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-341 A number or object is predictable based on observations that the attacker can make about the state of the system or network, such as time, process ID, etc.
CWE-283 The product does not properly verify that a critical resource is owned by the proper entity.

Attack-Flow Graph

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Executive Summary

This vulnerability involves a missing S3 bucket ownership verification in the AWS Security Agent MCP server before version 0.2.0. Attackers can exploit it by pre-registering an S3 bucket with a name derived from a publicly known AWS account identifier. When the server uploads scanned workspace archives, it may send sensitive data like credentials and infrastructure state to the attacker-controlled bucket.

Detection Guidance

To detect this vulnerability, check if your scan output bucket (security-agent-scans-<account-id>-<region>) is owned by your AWS account. Verify bucket ownership using AWS CLI commands like 'aws s3api list-buckets' and 'aws s3api get-bucket-acl'. Ensure the bucket name matches your account ID and region.

Impact Analysis

If exploited, attackers could access private source archives of scanned workspaces, including sensitive credentials and infrastructure state. This could lead to unauthorized access to systems, data breaches, or further compromise of your AWS environment. The impact depends on the sensitivity of the data stored in the scanned workspaces.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, which may violate compliance requirements under GDPR, HIPAA, or other regulations. Exposure of credentials or infrastructure state could result in data breaches, triggering mandatory breach notifications and potential fines or penalties.

Mitigation Strategies

Upgrade the AWS Security Agent MCP server to version 0.2.0 or later. Verify ownership of the scan-output bucket (security-agent-scans-<account-id>-<region>) to ensure it is owned by your AWS account. Pre-create the bucket in your own account to prevent third-party registrations of predictable bucket names.

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