Backstage Scaffolder plugin has insecure sandbox
Date: 2023-06
Affected: npm/@backstage/plugin-scaffolder-backend
Attack vector: rce
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2023-35926
CWE: CWE-94
CVSS: 8 (CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H)

The Backstage scaffolder-backend plugin uses a templating library that requires a sandbox, as it by design allows for code injection. The library used for this sandbox so far has been `vm2`, but in light of several past vulnerabilities and existing vulnerabilities that may not have a fix, the plugin has switched to using a different sandbox library. ### Impact A malicious actor with write access to a registered scaffolder template could manipulate the template in a way that allows for remote code execution on the scaffolder-backend instance. This was only exploitable in the template YAML definition itself and not by user input data. ### Patches This is vulnerability is fixed in version 1.15.0 of `@backstage/plugin-scaffolder-backend`. ### Workarounds Note that the [Backstage Threat Model](https://backstage.io/docs/overview/threat-model) states that scaffolder templates are considered to be a sensitive area that with the recommendation that you control access and perform manual reviews of changes to the scaffolder templates. The exploit is of a nature where it is easily discoverable in manual review.


Mitigations:

Architectural layers (MAESTRO):