# CVE-2026-106509: Backstage plugin-techdocs-node code execution in mkdocs configuration

Source: https://junglewise.ai/threats/cve-2026-106509-backstage-is-an-open-framework-for-building-developer-portals  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-06. Updated: 2026-10-06  
License: CC BY 4.0 with a link back

CVE-2026-106509 · Severity: high · CVSS 7.7 · Published 2026-10-06

Backstage is an open framework for building developer portals. The TechDocs plugin allows users to build and host technical documentation. Prior to version 1.14.6, a user with write access to a registered repository can inject malicious configuration values into mkdocs.yml that cause arbitrary code execution when documentation is built locally or in a container, giving an attacker command execution on the build system.

Technologies: [@backstage/plugin-techdocs-node (npm)](https://junglewise.ai/threats/technologies/npm-backstage-plugin-techdocs-node), [Spotify Backstage](https://junglewise.ai/threats/technologies/spotify-backstage). Vendors: [npm](https://junglewise.ai/threats/vendors/npm), [Spotify](https://junglewise.ai/threats/vendors/spotify).

## Quick answers

**Is CVE-2026-106509 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-106509 being exploited in the wild.

**How severe is CVE-2026-106509?** High severity, with a CVSS score of 7.7, published 6 October 2026.

**Which products and versions are affected?** @backstage/plugin-techdocs-node (npm) < 1.15.4, SEMVER:introduced=0,fixed=1.15.4; Spotify Backstage prior to 1.14.6, 1.15.4.

**Is there a fix for CVE-2026-106509?** Yes. @backstage/plugin-techdocs-node (npm): upgrade to 1.15.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-106509 attacked?** It is attacked with local access or over the network, in a software library.

**Am I affected by CVE-2026-106509?** Check whether you run @backstage/plugin-techdocs-node (npm) or Spotify Backstage 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-techdocs-node (npm): upgrade to 1.15.4 or later

  ```sh
  npm install @backstage/plugin-techdocs-node@1.15.4
  ```


## Technical details

The @backstage/plugin-techdocs-node package fails to properly sanitize mkdocs theme configuration and markdown_extensions in mkdocs.yml files, allowing injection of arbitrary extension configurations. An attacker with repository write access can craft nested configuration keys and theme options that are evaluated during the documentation build process, achieving remote code execution. The fix hardens mkdocs.yml configuration sanitization to block dangerous nested configuration keys and theme options.

## Affected products

- Spotify Backstage prior to 1.14.6, 1.15.4

## Identifiers

- CVE-2026-106509
- GHSA-8w7q-29mw-gf5c

## Timeline

- 2026-10-06: disclosed

## References

- [https://github.com/backstage/backstage/commit/02cd7cdbb18b687446277b5602adaee7f1d53cbb](https://github.com/backstage/backstage/commit/02cd7cdbb18b687446277b5602adaee7f1d53cbb)
- [https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9d](https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9d)

## Related threats

- [Backstage TechDocs remote code execution via mkdocs.yml](https://junglewise.ai/threats/cve-2026-106510-backstage-remote-code-execution-via-crafted-markdown-extensions)
- [Backstage plugin-techdocs-node code execution in MkDocs configuration](https://junglewise.ai/threats/cve-2026-106558-backstage-improper-validation-of-techdocs-mkdocs-configuration)
- [Backstage improper input validation in TechDocs Markdown extension](https://junglewise.ai/threats/cve-2026-106557-backstage-has-improper-input-validation-in-techdocs-markdown)
- [Backstage TechDocs local publisher path traversal](https://junglewise.ai/threats/cve-2026-106508-backstage-is-an-open-framework-for-building-developer-portals)
- [Backstage scaffolder task list input validation vulnerability](https://junglewise.ai/threats/cve-2026-106506-backstage-is-an-open-framework-for-building-developer-portals)