CVE-2026-106494 is a medium-severity (CVSS 4.4) Path Traversal vulnerability in @backstage/backend-defaults. A fix is available for @backstage/backend-defaults — see the affected versions and patch details below.
Backstage: Improper input validation in cloud storage URL readers
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-106494.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-106494 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
@backstage/backend-defaultsReal-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
Backstage is an open framework for building developer portals. Prior to 0.17.8, the @backstage/backend-defaults package is affected by improper input validation in cloud storage url readers. An attacker with write access to a cloud storage bucket used by Backstage could craft object names that could collide with protected files in the output directory. In certain deployment configurations, this could lead to content injection. This issue is fixed in version 0.17.8.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @backstage/backend-defaults | all versions | 0.17.8npm install @backstage/backend-defaults@0.17.8 |
Affected Products
backstagelinuxfoundationbackstage\/backend defaultslinuxfoundationDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @backstage/backend-defaults, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @backstage/backend-defaults to 0.17.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-106494 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Red Hat has evaluated this vulnerability as having Moderate severity because an attacker must already possess elevated permissions to write into the backing cloud storage environment, limiting the overall attack surface. Within Red Hat Developer Hub and Ansible Automation Platform environments, improper validation…
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.Source: Red Hat security advisory for CVE-2026-106494 (CC BY 4.0)
Frequently Asked Questions
Is CVE-2026-106494 in your dependencies?
Find it across npm, including transitive dependencies.