CVE-2026-64679 in Atlantis
Summary
by MITRE • 08/22/2026
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.
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Analysis
by VulDB Data Team • 08/22/2026
The vulnerability identified in Atlantis versions ranging from 0.19.8 to 0.45.0 represents a critical path traversal flaw rooted in insufficient input validation within the application's workspace management logic. Atlantis, a self-hosted Go-based tool designed to automate Terraform workflows via webhooks for pull requests, relies on constructing local file system paths based on user-supplied configuration data and API inputs. Specifically, when processing repository-level atlantis.yaml configurations or accepting authenticated requests through the /api/plan endpoint, the application incorporates workspace values directly into path construction without rigorous sanitization of traversal sequences such as dot-dot-slash patterns. This lack of consistent validation allows an attacker to manipulate these input parameters to escape the intended per-pull request working directory structure.
From a technical perspective, the core issue lies in how Atlantis joins user-controlled strings with base directories before verifying their validity against Terraform's constraints. The application proceeds to execute filesystem operations such as os.RemoveAll and os.MkdirAll on paths derived from these unsanitized inputs prior to any subsequent validation by the underlying Terraform engine. Because Terraform typically rejects invalid workspace names only after path construction has already occurred, the operating system executes destructive or constructive file system commands based on the attacker-controlled traversal segments. This sequence of operations enables an adversary to target arbitrary directories outside the designated sandboxed environment for pull requests, effectively bypassing the intended isolation boundaries established by the application's design.
The operational impact of this vulnerability is severe, encompassing both integrity loss and denial of service conditions. By exploiting the path traversal flaw, a malicious actor with access to the Atlantis webhook interface or API can create new directories in sensitive locations, delete critical files within out-of-bounds paths, or overwrite existing writable resources on the host system running the Atlantis process. Since these operations are executed with the privileges of the Atlantis service account, which often requires elevated permissions to manage infrastructure state and clone repositories, the potential for systemic compromise is significant. An attacker could potentially disrupt ongoing deployments by deleting necessary files, corrupt project states by modifying configuration outside expected paths, or establish persistence mechanisms through unauthorized directory creation, thereby undermining the reliability and security of the continuous integration pipeline.
This vulnerability aligns with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, as it involves accessing resources outside the intended restricted location due to insufficient validation of user input. Furthermore, from an offensive cybersecurity framework perspective, this flaw facilitates techniques associated with ATT&CK T1083: File and Directory Discovery or potentially T1496: Resource Hijacking if used for denial-of-service purposes by consuming system resources through excessive file operations. The exploitation chain relies on the attacker's ability to submit crafted workspace names via accepted configuration files or API calls, leveraging the application's trust in these inputs before they are processed by Terraform.
Mitigation strategies must prioritize immediate upgrading to version 0.45.0 or later, where this path traversal issue has been resolved through enhanced input validation and stricter enforcement of directory boundaries. For organizations unable to upgrade immediately, implementing strict network-level controls such as web application firewalls can help filter out requests containing suspicious path traversal patterns in the relevant API endpoints and webhook payloads. Additionally, running Atlantis with minimal necessary privileges using principle of least privilege principles can limit the blast radius if an exploitation attempt occurs. Regular auditing of atlantis.yaml configurations for unexpected workspace definitions and monitoring file system activity on the host machine for anomalous creation or deletion events outside expected project directories are recommended defensive measures to detect potential abuse attempts while patching is underway.