A flaw in OpenStack Keystone allows a user with a restricted application credential and only reader role to call the EC2 credential creation API and obtain an EC2/S3 credential that inherits the full set of the parent user’s S3 permissions. The result is a privilege escalation that bypasses the intended role restrictions on the application credential. The weakness is rooted in improper account and privilege management and missing authorization checks.

Vulnerable versions of OpenStack Keystone are 14 through 26 before 26.1.1, as well as 27.0.0, 28.0.0, and 29.0.0. The issue manifests only when restricted application credentials are used alongside the EC2/S3 compatibility API (swift3 / s3api).

The CVSS score of 3.5 indicates a moderate impact, while an EPSS score below 1% suggests a low likelihood of exploitation in the wild. The vulnerability is not listed in CISA’s KEV catalog. Based on the description, it is inferred that the attacker must already be authenticated, possess a reader role, and have access to a restricted application credential. The attack vector is therefore internal or requires a compromised user credential rather than remote exploitation.