# CVE-2026-83551: Amazon SageMaker Python SDK cleartext HMAC key storage

Source: https://junglewise.ai/threats/cve-2026-83551-amazon-sagemaker-python-sdk-cleartext-hmac-key-storage  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-01. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-83551 · Severity: high · CVSS 7.2 · Published 2026-09-01

The SageMaker Python SDK's pipeline decorator components use HMAC keys to verify the integrity of code payloads stored in AWS S3. A vulnerability exposes these signing keys in cleartext within pipeline definitions, allowing anyone with describe-pipeline permissions in the AWS account to retrieve them, forge valid payloads, and execute arbitrary code in another user's pipeline context. This breaks the security boundary for teams sharing an AWS account and could lead to unauthorized data access or malicious code execution.

Technologies: [Amazon AWS](https://junglewise.ai/threats/technologies/aws), [Amazon SageMaker Python SDK](https://junglewise.ai/threats/technologies/sagemaker-python-sdk). Vendors: [Amazon](https://junglewise.ai/threats/vendors/amazon).

## Quick answers

**Is CVE-2026-83551 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-83551 being exploited in the wild.

**How severe is CVE-2026-83551?** High severity, with a CVSS score of 7.2, published 1 September 2026.

**Which products and versions are affected?** Amazon SageMaker Python SDK v3 < 3.11.0, v2 < 2.256.0.

**Is there a fix for CVE-2026-83551?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-83551 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-83551?** Check whether you run Amazon AWS or Amazon SageMaker Python SDK at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The SageMaker Python SDK uses HMAC keys to cryptographically sign serialized function payloads that are stored in S3 as part of pipeline definitions. The vulnerability is a cleartext storage issue: these secret keys are embedded unencrypted in the pipeline definition document and exposed via the DescribePipeline API call. An attacker with an IAM role that has DescribePipeline permissions can call the API, retrieve the HMAC key from the pipeline metadata, and then craft valid cloud-pickled payloads with correct HMACs. The attacker can then overwrite S3 objects to inject malicious code that executes during another user's pipeline execution context. The precondition is IAM permissions to invoke DescribePipeline within the same AWS account; the attack is unauthenticated once those permissions are obtained. Patches are available in SageMaker Python SDK v3.11.0+ and v2.256.0+.

## Affected products

- Amazon SageMaker Python SDK v3 < 3.11.0, v2 < 2.256.0

## Timeline

- 2026-09-09: disclosed
- 2026-09-01: advisory: AWS Security Bulletin 2026-093-AWS published

## References

- [https://aws.amazon.com/security/security-bulletins/rss/2026-093-aws/](https://aws.amazon.com/security/security-bulletins/rss/2026-093-aws/)

## Related threats

- [An untrusted search path issue in Aurora PostgreSQL dialect detection in the AWS Advanced Go Wrapper from release 2026-04-06 (awssql/v2.0.0)](https://junglewise.ai/threats/cve-2026-126793-privilege-escalation-in-aurora-postgresql-dialect-detection-in)
- [AWS SDK for pandas EMR unverified bucket ownership](https://junglewise.ai/threats/cve-2026-127119-unverified-ownership-of-the-default-emr-cluster-log-location-in)
- [Amazon mcp-gateway-registry server-side request forgery in registration API](https://junglewise.ai/threats/cve-2026-125926-server-side-request-forgery-in-the-server-registration-and)
- [Amazon mcp-gateway-registry authorization bypass in management API](https://junglewise.ai/threats/cve-2026-100307-missing-authorization-on-the-external-management-api-in-mcp)
- [AWS Kiro CLI incorrect default permissions on session files](https://junglewise.ai/threats/cve-2026-124848-incorrect-default-permissions-on-session-transcripts-and-prompt)