DEV Community

CVE Reports
CVE Reports

Posted on • Originally published at cvereports.com

CVE-2026-1777: SageMaker's Open Secret: How a Helper Function Became a Backdoor

#security #cve #cybersecurity

SageMaker's Open Secret: How a Helper Function Became a Backdoor

Vulnerability ID: CVE-2026-1777
CVSS Score: 7.2
Published: 2026-02-02

A critical design flaw in the Amazon SageMaker Python SDK allowed for Remote Code Execution (RCE) via insecure handling of cryptographic secrets. The SDK's 'remote function' capability, designed to offload local Python code to AWS training clusters, utilized a HMAC integrity check to sanitize serialized payloads. However, the secret key for this check was transmitted as a cleartext environment variable, accessible via standard AWS APIs. This allowed attackers with moderate privileges to forge malicious pickle payloads, achieving code execution both on the AWS training infrastructure and potentially on the victim developer's local machine.

TL;DR

The SageMaker Python SDK passed its integrity secret key as a cleartext environment variable. Anyone with 'DescribeTrainingJob' permissions could read the key, forge malicious serialized objects, and execute code on the training cluster or the developer's laptop.

⚠️ Exploit Status: POC

Technical Details

  • CWE ID: CWE-312 (Cleartext Storage of Sensitive Information)
  • Attack Vector: Network (API & S3)
  • CVSS v3.1: 7.2 (High)
  • Impact: Remote Code Execution (RCE)
  • Authentication: Required (AWS IAM)
  • Exploit Status: PoC Possible (Logic is public)

Affected Systems

  • Amazon SageMaker Python SDK (v2 < 2.256.0)
  • Amazon SageMaker Python SDK (v3 < 3.2.0)
  • MLOps Pipelines utilizing @remote decorator
  • sagemaker: < 3.2.0 (Fixed in: 3.2.0)
  • sagemaker: < 2.256.0 (Fixed in: 2.256.0)

Code Analysis

Commit: fb0d789

Fix for V3: Remove HMAC integrity check and reliance on env var secrets

- hmac.new(secret_key.encode()...
+ hashlib.sha256(buffer)...
Enter fullscreen mode Exit fullscreen mode

Commit: 708c7b2

Fix for V2: Backport of integrity check removal

Similar removal of HMAC logic
Enter fullscreen mode Exit fullscreen mode

Exploit Details

  • Internal Research: Exploit methodology involves standard AWS CLI commands and Python pickle generation.

Mitigation Strategies

  • Upgrade SageMaker SDK immediately.
  • Restrict 'sagemaker:DescribeTrainingJob' permissions.
  • Lock down S3 Bucket Policies for training artifacts.

Remediation Steps:

  1. Run pip install --upgrade sagemaker to ensure version 3.2.0+ or 2.256.0+.
  2. Audit IAM roles to ensure developers do not have broad write access to S3 buckets used by other teams.
  3. Enable Server-Side Encryption with KMS (SSE-KMS) for S3 buckets. This adds an IAM layer (kms:Decrypt) required to read/execute artifacts, mitigating simple S3 write exploits.

References

Read the full report for CVE-2026-1777 on our website for more details including interactive diagrams and full exploit analysis.

Top comments (0)