This vulnerability (CWE-732) arises from incorrect permission assignment for critical resources in AWS CLI on Unix-like systems. Specifically, when the default umask does not restrict file permissions, credentials written by subcommands such as aws codeartifact login, aws iam create-virtual-mfa-device, and aws deploy register may be readable by other local users. This affects AWS CLI versions prior to 1.44.78 (v1) and 2.34.29 (v2). The CVSS 3.1 base score is 5.5 (medium severity), reflecting local attack vector with low complexity and no user interaction, impacting confidentiality but not integrity or availability. AWS has published an advisory and users are advised to upgrade to the fixed versions.

The vulnerability allows local users on the same Unix-like host to read AWS credentials created by certain CLI subcommands due to overly permissive file permissions. This compromises confidentiality of credentials but does not affect integrity or availability. Exploitation requires local access and low privileges. No known exploits in the wild have been reported.

A patch is available. Users should upgrade AWS CLI to version 1.44.78 (v1) or 2.34.29 (v2) or later to remediate this issue. Since this is a client-side tool, remediation is managed by the user upgrading their installed AWS CLI version. Refer to the official AWS security bulletin at https://aws.amazon.com/security/security-bulletins/2026-049-aws/ for detailed guidance.