Live › vulnerability › GHSA-5rx8-8fr2-f855
Go to dashboardThe SageMaker Python SDK's default_bucket() uses a predictably named S3 bucket without checking the caller's account owns it. An attacker who pre-creates that bucket can get code run in a SageMaker execution environment and obtain IAM credentials.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-24 19:12 UTC. All times on this page are UTC.
Teams using the Amazon SageMaker Python SDK V2 before 2.257.3 or V3 from 3.0.0 before 3.10.0 that rely on the auto-generated default bucket name. Code that passes its own owned bucket explicitly to sagemaker.Session is not exposed through this path. Teams not using the SageMaker SDK can skip it.
No product ranges from the sources yet.
pip show sagemaker and compare against the fixed versions.default_bucket() or sagemaker.Session without an explicit default_bucket argument in your code.2.257.3 on the V2 line or 3.10.0 on the V3 line.default_bucket parameter of sagemaker.Session or the SageMaker SDK configuration file.Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
CVE-2026-112408 - Missing bucket ownership verification in Amazon SageMaker Python SDK default_bucket()
Bulletin ID: 2026-142-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 10/21/2026 12:30 PM PDT
Description:
The Amazon SageMaker Python SDK is an open-source library for training and deploying machine learning models on Amazon SageMaker. We identified CVE-2026-112408, an issue in the default_bucket() function. The SDK uses a predictably named Amazon S3 bucket and does not check that the caller's AWS account owns it. A remote actor who creates that bucket first could achieve code execution in a remote SageMaker execution environment and obtain IAM credentials.
Impacted versions:
Resolution:
This issue has been addressed in Amazon SageMaker Python SDK versions 2.257.3 (V2) and 3.10.0 (V3). We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.
Workarounds:
If you are not able to upgrade, pass an S3 bucket that your account owns explicitly through the default_bucket parameter of sagemaker.Session (or through the SageMaker SDK configuration file). Do not rely on the auto-generated default bucket name.
References:
Acknowledgement:
We would like to thank Dan Gansel from Upwind Security for collaborating on this issue through the coordinated disclosure process.
Please email [email protected] with any security questions or concerns.
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