# CVE-2026-106494: Backstage backend-defaults path traversal in cloud storage URL readers

Source: https://junglewise.ai/threats/cve-2026-106494-backstage-is-an-open-framework-for-building-developer-portals  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-06. Updated: 2026-10-06  
License: CC BY 4.0 with a link back

CVE-2026-106494 · Severity: medium · CVSS 4.4 · Published 2026-10-06

Backstage is an open-source developer portal framework. The backend-defaults package improperly validates object names from cloud storage buckets, allowing attackers with write access to craft malicious names that collide with protected files. In certain deployments, this could lead to unauthorized content injection into the application's output directory.

Technologies: [Backstage Backend-Defaults](https://junglewise.ai/threats/technologies/backend-defaults), [@backstage/backend-defaults (npm)](https://junglewise.ai/threats/technologies/backstage-backend-defaults). Vendors: [Backstage](https://junglewise.ai/threats/vendors/backstage), [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-106494 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-106494 being exploited in the wild.

**How severe is CVE-2026-106494?** Medium severity, with a CVSS score of 4.4, published 6 October 2026.

**Which products and versions are affected?** Backstage Backend-Defaults prior to 0.17.8; @backstage/backend-defaults (npm) < 0.17.8, SEMVER:introduced=0,fixed=0.17.8.

**Is there a fix for CVE-2026-106494?** Yes. @backstage/backend-defaults (npm): upgrade to 0.17.8 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-106494 attacked?** It is attacked from the adjacent network, in a software library.

**Am I affected by CVE-2026-106494?** Check whether you run Backstage Backend-Defaults or @backstage/backend-defaults (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- @backstage/backend-defaults (npm): upgrade to 0.17.8 or later

  ```sh
  npm install @backstage/backend-defaults@0.17.8
  ```


## Technical details

The @backstage/backend-defaults package lacks proper input validation in cloud storage URL readers, allowing path traversal attacks via crafted object names. An attacker with write access to a cloud storage bucket can create objects with names designed to collide with and overwrite protected files in the output directory. Exploitation requires both cloud storage bucket write access and a vulnerable deployment configuration; the issue is fixed by validating and sanitizing paths in the cloud storage reader.

## Affected products

- Backstage backend-defaults prior to 0.17.8

## Identifiers

- CVE-2026-106494
- GHSA-7649-wm97-w3j3

## Timeline

- 2026-10-06: disclosed

## References

- [https://github.com/backstage/backstage/commit/14e925ce5b905dd8daa64c3009722febda76034c](https://github.com/backstage/backstage/commit/14e925ce5b905dd8daa64c3009722febda76034c)
- [https://github.com/backstage/backstage/releases/tag/v1.54.6](https://github.com/backstage/backstage/releases/tag/v1.54.6)

## Related threats

- [Backstage backend-defaults improper access control in action invocation](https://junglewise.ai/threats/cve-2026-106495-backstage-improper-access-control-in-backend-action-invocation)
- [Backstage: Cloud storage catalog locations may cross configured storage boundaries](https://junglewise.ai/threats/cve-2026-106493-backstage-is-an-open-framework-for-building-developer-portals)
- [Backstage backend-defaults service credential delegation bypass](https://junglewise.ai/threats/cve-2026-106492-backstage-is-an-open-framework-for-building-developer-portals)
- [Backstage Scaffolder symlink path traversal in multiple actions](https://junglewise.ai/threats/cve-2026-24046-backstage-scaffolder-symlink-path-traversal-in-multiple-actions)
- [Backstage SSRF in FetchUrlReader via HTTP redirects](https://junglewise.ai/threats/cve-2026-24048-backstage-ssrf-in-fetchurlreader-via-http-redirects)