@backstage/cli-common has a possible `resolveSafeChildPath` Symlink Chain Bypass
Impact
The resolveSafeChildPath utility function in @backstage/backend-plugin-api, which is used to prevent path traversal attacks, failed to properly validate symlink chains and dangling symlinks. An attacker could bypass the path validation by:
- Symlink chains: Creating
link1 → link2 → /outsidewhere intermediate symlinks eventually resolve outside the allowed directory - Dangling symlinks: Creating symlinks pointing to non-existent paths outside the base directory, which would later be created during file operations
This function is used by Scaffolder actions and other backend components to ensure file operations stay within designated directories.
Patches
This vulnerability is fixed in @backstage/backend-plugin-api version 0.1.17. Users should upgrade to this version or later.
Workarounds
- Run Backstage in a containerised environment with limited filesystem access
- Restrict template creation to trusted users
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | @backstage/cli-common | < 0.1.17 | 0.1.17 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N- Weakness (CWE)
CWE-59, CWE-61- Platform
- npm
- Package
@backstage/cli-common- Disclosed
- 21.01.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-2p49-45hj-7mc9 - CC BY 4.0
Vulnerability history: @backstage/cli-common
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
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