CVE-2021-43783 : Security Advisory and Response

This CVE involves a path traversal vulnerability in @backstage/plugin-scaffolder-backend, affecting versions prior to 0.15.14, allowing malicious actors to manipulate templates and write files to arbitrary paths on the host instance.

Understanding CVE-2021-43783

This vulnerability scored a CVSS base score of 8.5 (High severity) and falls under CWE-22 (Improper Limitation of a Pathname to a Restricted Directory).

What is CVE-2021-43783?

In affected versions, attackers with write access can manipulate templates to write files to arbitrary paths on the host.
Exploitation can occur through user input execution without write access.
The vulnerability is resolved in version 0.15.14 of @backstage/plugin-scaffolder-backend.

The Impact of CVE-2021-43783

CVSS Score: 8.5 (High)
Attack Vector: Network
Integrity Impact: High
Privileges Required: Low
Scope: Changed

Technical Details of CVE-2021-43783

This section dives into the technical aspects of the vulnerability.

Vulnerability Description

Malicious actors can write files to arbitrary paths on the host instance by manipulating scaffolder templates.

Affected Systems and Versions

Product: Backstage
Versions Affected: < 0.15.14

Exploitation Mechanism

Attackers with write access can craft templates to write files to arbitrary paths without needing user input to control file contents.

Mitigation and Prevention

Learn how to mitigate this vulnerability.

Immediate Steps to Take

Upgrade @backstage/plugin-scaffolder-backend to version 0.15.14.
Restrict access to scaffolder templates.
Require reviews when registering or modifying templates.

Long-Term Security Practices

Regularly review and update access controls.
Implement strict input validation to prevent template manipulation.
Educate users on secure template usage.

Patching and Updates

Ensure timely installation of software updates and patches.