CVE-2026-64679: Improper Limitation of a Pathname to a Restricted Directory

Atlantis is a self-hosted golang application that listens for Terraform pull request events via webhooks. From 0.19.8 until 0.45.0, Atlantis does not consistently validate user-controlled workspace values supplied through accepted repository-level atlantis.yaml configuration or authenticated /api/plan input before joining them into local workspace paths. Traversal segments can escape the intended per-pull workspace directory and cause clone preparation or other working-directory code paths to call os.RemoveAll, os.MkdirAll, or related filesystem operations on out-of-bounds directories before Terraform rejects the invalid workspace name. This can create, delete, or reuse writable paths with the privileges of the Atlantis process, causing integrity loss or denial of service. This issue is fixed in version 0.45.0.