CVE-2026-127119 · Package
NO FIX YET · SEE WHAT TO DO
When awswrangler creates an EMR cluster without an explicit log location, it writes logs to a predictable default S3 bucket name without checking that the caller's account owns it. A remote attacker who creates that bucket first can read the cluster's logs, including job step output.
first public Nov 12, 2026 · 2 sources
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Teams using awswrangler from 1.1.0 before 3.18.0 to create Amazon EMR clusters without passing an explicit log location. Code that always passes an explicit log location pointing to a bucket the team owns is not exposed. The default bucket name is predictable, so an attacker in another account can create it first and collect logs.
Not affected if explicit-log-location, no-emr-usage, version-3.18.0-or-later
Who cares aws, awswrangler, emr, lab-disclosure, python
pip show awswrangler and compare against the affected range.aws-logs-{account}-{region} exists in each region you use and whether your account owns it.awswrangler 3.18.0: upgrade to this version or later; the release requires s3:ListBucket on the default log bucket to verify ownership.CVE-2026-127119 - Unverified ownership of the default EMR cluster log location in AWS SDK for pandas
Bulletin ID: 2026-181-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 11/12/2026 10:45 PM PST
Description:
AWS SDK for pandas (awswrangler) is an open-source Python library that integrates pandas with AWS services, including Amazon EMR.
We identified CVE-2026-127119, an issue in the EMR module of AWS SDK for pandas (awswrangler) from version 1.1.0 before 3.18.0. When a cluster is created without an explicit log location, the library uses a predictable default S3 bucket name for the cluster logs without verifying that the caller's account owns that bucket. A remote actor who creates that bucket first could read the cluster's logs, including job step output.
Impacted versions: >= 1.1.0 AND < 3.18.0
Resolution:
This issue has been addressed in awswrangler version 3.18.0. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes. Users who rely on the default log location should also make sure the caller has s3:ListBucket on the default log bucket, which version 3.18.0 requires to verify bucket ownership.
Workarounds:
If you cannot upgrade immediately, pass an explicit log location that points to a bucket you own when creating clusters with AWS SDK for pandas, or create the default EMR log bucket (aws-logs-{account}-{region}) in your own account in each region you use. If that bucket name is already taken by another account, treat it as untrusted and use an explicit log location.
References:
Acknowledgement:
We would like to thank Upwind Security for collaborating on this issue through the coordinated vulnerability disclosure process.
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