AWS SageMaker Python SDK CVE-2026-1777 RCE via HMAC Key Leakage

Vulnerability Key Information Vulnerability Overview Package: sagemaker-python-sdk CVE ID: CVE-2026-1777 Severity: High Affected Versions: <3.2.0 Patched Versions: 3.2.0 Vulnerability Description The SageMaker Python SDK is used for training and deploying machine learning models on Amazon SageMaker. We discovered an issue where HMAC keys are stored in environment variables and leaked via the DescribeTrainingJob API. Impact Function and Payload Tampering: Attackers with DescribeTrainingJob permissions can extract HMAC keys and forge serialized function payloads stored in S3. These tampered payloads will be processed and executed without triggering integrity validation errors, leading to unintended code replacement. Arbitrary Code Execution in Training Environments: Attackers can exploit DescribeTrainingJob permissions along with write access to the job’s S3 output location to extract HMAC keys, create malicious Python objects, and achieve remote code execution. Data and Credential Handling: Arbitrary remote code execution may interact with sensitive data, model artifacts, environment variables, and potentially AWS metadata. Cross-Tenant or Shared Environment Risks: In multi-tenant or shared S3 buckets, leaked HMAC keys can serve as an attack vector, enabling improper operations using others’ remote function workloads. Affected Versions SageMaker Python SDK v3 < v3.2.0 SageMaker Python SDK v2 < v2.256.0 Patch This issue has been fixed in SageMaker Python SDK versions v3.2.0 and v2.256.0. We recommend upgrading to the latest version immediately and ensuring any forks or derived code include the new fix. Mitigation Customers using self-signed certificates should add their private Certificate Authority (CA) certificate to the container image, rather than relying on the SDK’s previously insecure configuration. This selective approach maintains security while adapting to internal trusted domains. References For any questions or feedback regarding this advisory, please contact us via our vulnerability reporting page or directly by email at aws-security@amazon.com. Please do not create public issues on GitHub.

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AWS SageMaker Python SDK CVE-2026-1777 RCE via HMAC Key Leakage

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