CVE-2021-43783 Path Traversal in @backstage/plugin-scaffolder-backend
Attackers can write files to arbitrary paths on the host via template manipulation or user input, potentially leading to code execution.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-43783?
CVE-2021-43783 is a high-severity path traversal vulnerability in Linuxfoundation Backstage, published on 29 Nov 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
@backstage/plugin-scaffolder-backend is the backend for the default Backstage software templates. In affected versions a malicious actor with write access to a registered scaffolder template is able to manipulate the template in a way that writes files to arbitrary paths on the scaffolder-backend host instance. This vulnerability can in some situation also be exploited through user input when executing a template, meaning you do not need write access to the templates. This method will not allow the attacker to control the contents of the injected file however, unless the template is also crafted in a specific way that gives control of the file contents. This vulnerability is fixed in version `0.15.14` of the `@backstage/plugin-scaffolder-backend`. This attack is mitigated by restricting access and requiring reviews when registering or modifying scaffolder templates.
Weakness: CWE-22
Which versions are affected by CVE-2021-43783?
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 | 0.15.14 |
@backstage/plugin-scaffolder-backend npm | All versions | 0.15.14 |
Products include Linuxfoundation Backstage.
How do I fix CVE-2021-43783?
Upgrade @backstage/plugin-scaffolder-backend to 0.15.14 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2021-43783 being exploited?
There is no known exploitation of CVE-2021-43783 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-mg3m-f475-28hv.