Executive brief
Amazon CodeCatalyst is a cloud service that helps developers create projects from reusable templates. The underlying blueprints framework, used to build these templates, contained a vulnerability in how it processed project configuration files during resynthesis. An attacker with commit access could inject shell commands into the configuration file that would execute with the privileges of the resynthesis environment, potentially compromising credentials or project data. AWS has deployed server-side protections to prevent this attack, but users running the SDK locally should update to patched versions.
Technical details
The vulnerability is an OS command injection flaw in the blueprint resynthesis framework. During the resynthesis process, the framework reads the .ownership-file from an existing project to determine which files a blueprint is permitted to modify. In affected versions, the owner field from a [local] merge strategy entry was passed directly to an operating system command via shell invocation without proper validation or escaping. An attacker with repository commit access can craft a malicious .ownership-file containing shell metacharacters (e.g., backticks, pipes, semicolons) in the owner field to execute arbitrary commands in the resynthesis environment. The injected commands run with the privileges and credentials available to that environment. AWS mitigates this for the managed CodeCatalyst service through server-side validation that restricts [local] merge strategy commands to an allowlisted form. Users of the open-source npm package should update to version 0.3.156 or later.
Affected products
- Amazon @amazon-codecatalyst/blueprints.blueprint <= 0.3.155
Timeline
- 2026-09-09: disclosed: AWS security bulletin published
- 2026-09-03: other: Bulletin ID 2026-095-AWS released