CVE-2023-35926 Insecure sandbox in Backstage Scaffolder plugin
A malicious actor with write access to a scaffolder template can achieve remote code execution on the backend due to an insecure sandbox implementation.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-35926?
CVE-2023-35926 is a high-severity code injection vulnerability in Linuxfoundation Backstage, published on 22 Jun 2023. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
Backstage is an open platform for building developer portals. The Backstage scaffolder-backend plugin uses a templating library that requires 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. 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. This is vulnerability is fixed in version 1.15.0 of `@backstage/plugin-scaffolder-backend`.
Weakness: CWE-94
Which versions are affected by CVE-2023-35926?
2 open source packages ship an affected version, including @backstage/plugin-scaffolder-backend. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
@backstage/plugin-scaffolder-backend npm | All versions | 1.15.0 |
@backstage/plugin-scaffolder-backend npm | All versions | 1.15.0 |
Products include Linuxfoundation Backstage.
How do I fix CVE-2023-35926?
Upgrade @backstage/plugin-scaffolder-backend to 1.15.0 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2023-35926 being exploited?
There is no known exploitation of CVE-2023-35926 in the wild and no public exploit code.
Other vulnerabilities in Linuxfoundation Backstage
- CVE-2026-106501 Backstage: Sensitive information exposure in Scaffolder
- CVE-2026-106558 Backstage: Improper validation of TechDocs MkDocs configuration
- CVE-2026-88064 Backstage: Improper input validation in TechDocs MkDocs configuration
- CVE-2026-106459 Backstage: Improper input validation in Sentry scaffolder actions
- CVE-2026-106486 Backstage: Improper filesystem validation in Bitbucket pull-request scaffolder actions
Sources
Also known as GHSA-wg6p-jmpc-xjmr.