Backstage Scaffolder plugin has insecure sandbox
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 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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | @backstage/plugin-scaffolder-backend | < 1.15.0 | 1.15.0 |
References
- https://github.com/backstage/backstage/security/advisories/GHSA-wg6p-jmpc-xjmr
- https://nvd.nist.gov/vuln/detail/CVE-2023-35926
- https://github.com/backstage/backstage/commit/fb7375507d56faedcb7bb3665480070593c8949a
- https://github.com/backstage/backstage
- https://github.com/backstage/backstage/releases/tag/v1.15.0
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H- Weakness (CWE)
CWE-94- Platform
- npm
- Package
@backstage/plugin-scaffolder-backend- Disclosed
- 21.06.2023
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-wg6p-jmpc-xjmr - CC BY 4.0
Vulnerability history: @backstage/plugin-scaffolder-backend
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 17
- First → latest
- 10.2021 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 6
- Medium 8
- Low 2
Disclosures per year
- 2021: 3
- 2022: 0
- 2023: 1
- 2024: 0
- 2025: 1
- 2026: 12
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