# CVE-2021-41151: Backstage plugin-scaffolder-backend path traversal

Source: https://junglewise.ai/threats/cve-2021-41151-backstage-plugin-scaffolder-backend-path-traversal  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-10-19. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2021-41151 · Severity: low · CVSS 3.1 · Published 2021-10-19

Backstage's Scaffolder plugin (used to create new projects from templates) contains a path traversal vulnerability that allows an authenticated attacker to read sensitive files from the environment and exfiltrate them via GitHub pull requests. The attack requires the attacker to have permissions to create and register templates in the Backstage catalog, making it a restricted threat with moderate business impact.

Technologies: [Backstage Plugin-Scaffolder-Backend](https://junglewise.ai/threats/technologies/plugin-scaffolder-backend), [@backstage/plugin-scaffolder-backend (npm)](https://junglewise.ai/threats/technologies/backstage-plugin-scaffolder-backend). Vendors: [Backstage](https://junglewise.ai/threats/vendors/backstage), [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2021-41151 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2021-41151 being exploited in the wild.

**How severe is CVE-2021-41151?** Low severity, with a CVSS score of 3.1, published 19 October 2021.

**Which products and versions are affected?** Backstage Plugin-Scaffolder-Backend 0.9.4 to 0.15.8; @backstage/plugin-scaffolder-backend (npm) SEMVER:introduced=0.9.4,fixed=0.15.9.

**Is there a fix for CVE-2021-41151?** Yes. @backstage/plugin-scaffolder-backend (npm): upgrade to 0.15.9 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2021-41151 attacked?** It is attacked over the network.

**Am I affected by CVE-2021-41151?** Check whether you run Backstage Plugin-Scaffolder-Backend or @backstage/plugin-scaffolder-backend (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- @backstage/plugin-scaffolder-backend (npm): upgrade to 0.15.9 or later

  ```sh
  npm install @backstage/plugin-scaffolder-backend@0.15.9
  ```


## Technical details

The vulnerability is a path traversal flaw (CWE-22) in the @backstage/plugin-scaffolder-backend that affects versions 0.9.4 through 0.15.8. An authenticated attacker can exploit this by crafting a malicious Scaffolder template with a publish:github:pull-request action using a crafted source path that traverses the restricted directory and accesses arbitrary files. The vulnerability requires the attacker to have catalog template registration permissions, and the exfiltration method (via visible pull requests) makes the attack highly observable. The vulnerability is fixed in version 0.15.9 and later.

## Affected products

- Backstage plugin-scaffolder-backend 0.9.4 to 0.15.8

## Identifiers

- CVE-2021-41151
- GHSA-pvv8-8fx9-h673

## Timeline

- 2021-10-16: disclosed: Security advisory published
- 2021-10-19: patched: Fix available in version 0.15.9

## References

- [https://github.com/backstage/backstage/security/advisories/GHSA-pvv8-8fx9-h673](https://github.com/backstage/backstage/security/advisories/GHSA-pvv8-8fx9-h673)

## Related threats

- [Backstage scaffolder task list input validation vulnerability](https://junglewise.ai/threats/cve-2026-106506-backstage-is-an-open-framework-for-building-developer-portals)
- [Backstage scaffolder-backend sensitive information exposure in task logs](https://junglewise.ai/threats/cve-2026-106504-backstage-is-an-open-framework-for-building-developer-portals)
- [Backstage Scaffolder Backend authorization bypass in action input validation](https://junglewise.ai/threats/cve-2026-106503-backstage-is-an-open-framework-for-building-developer-portals)
- [Backstage plugin-scaffolder-backend credential exposure in task events](https://junglewise.ai/threats/cve-2026-106502-backstage-is-an-open-framework-for-building-developer-portals)
- [Backstage plugin-scaffolder-backend sensitive information exposure](https://junglewise.ai/threats/cve-2026-106501-backstage-is-an-open-framework-for-building-developer-portals)