CVE-2026-4269
Code Injection via Missing S3 Ownership Check in Bedrock AgentCore
Publication date: 2026-03-16
Last updated on: 2026-03-16
Assigner: AMZN
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| bedrock | agentcore_starter_toolkit | to 0.1.13 (exc) |
| aws | bedrock_agentcore_starter_toolkit | to 0.1.13 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-340 | The product uses a scheme that generates numbers or identifiers that are more predictable than required. |
| CWE-283 | The product does not properly verify that a critical resource is owned by the proper entity. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
CVE-2026-4269 is a vulnerability in the Bedrock AgentCore Starter Toolkit versions before v0.1.13 caused by missing S3 ownership verification. This flaw allows a remote attacker to inject malicious code during the build process of the toolkit. As a result, the attacker can execute arbitrary code within the AgentCore Runtime environment.
This issue only affects users who built the toolkit after September 24, 2025, on versions prior to v0.1.13. Users on version v0.1.13 or later, or those who built earlier versions before that date, are not affected.
How can this vulnerability impact me? :
The vulnerability can allow a remote attacker to inject and execute arbitrary code in the AgentCore Runtime. This could lead to unauthorized actions being performed within the runtime environment, potentially compromising the security and integrity of systems using the affected toolkit.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should upgrade the Bedrock AgentCore Starter Toolkit to version v0.1.13 or later.
This upgrade ensures proper S3 ownership verification and prevents remote code injection during the build process.
Users who have built the toolkit after September 24, 2025 on versions prior to v0.1.13 are affected and should upgrade immediately.