GHSA-2p49-45hj-7mc9
MEDIUM@backstage/cli-common has a possible `resolveSafeChildPath` Symlink Chain Bypass
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
@backstage/cli-commonReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @backstage/cli-common | all versions | 0.1.17 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @backstage/cli-common. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @backstage/cli-common to 0.1.17 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2p49-45hj-7mc9 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-2p49-45hj-7mc9 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-2p49-45hj-7mc9. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-2p49-45hj-7mc9 in your dependencies?
O3 detects GHSA-2p49-45hj-7mc9 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.