Backstage: Improper task state validation in Scaffolder backend

ALTO 8.5CVE-2026-106500 · GHSA-xvgh-hmx8-9xxf · Published 06/10/2026 · updated 13/10/2026

Package	Affected versions	Patched versions
backstage linuxfoundation	`≥ 1.50.0, < 1.50.5≥ 1.51.0, < 1.54.6< 1.49.6`	`1.50.51.54.61.49.6`
backstage/plugin-scaffolder-backend linuxfoundation	`≥ 3.4.0, < 3.4.1≥ 4.0.0, < 4.0.3≥ 4.0.4, < 4.1.0< 3.3.1`	`3.4.14.0.34.1.03.3.1`
@backstage/plugin-scaffolder-backend npm	`< 4.1.0`	`4.1.0`

Description

Impact

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.

Patches

Patched in @backstage/plugin-scaffolder-backend version 4.1.0

Workarounds

Restrict Scaffolder task creation and task-read permissions to trusted users through the permission policy.
Limit who can register or modify templates and which Scaffolder actions may execute.
Run backend application files read-only outside a dedicated, least-privilege Scaffolder working directory.

References

Authorizing Scaffolder tasks, parameters, steps, and actions

NVD 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.

References

backstage/backstage security advisory · WEB
nvd.nist.gov/vuln/detail/CVE-2026-106500 · ADVISORY
backstage/backstage commit 0d24f1b · WEB
backstage/backstage commit 56be299 · WEB
backstage/backstage commit 9e86c95 · WEB
backstage/backstage · PACKAGE
backstage/backstage release v1.49.6 · WEB
backstage/backstage release v1.50.5 · WEB
backstage/backstage release v1.54.6 · WEB

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Package

Affected versions

Patched versions

backstage

linuxfoundation

≥ 1.50.0, < 1.50.5≥ 1.51.0, < 1.54.6< 1.49.6

1.50.51.54.61.49.6

backstage/plugin-scaffolder-backend

linuxfoundation

≥ 3.4.0, < 3.4.1≥ 4.0.0, < 4.0.3≥ 4.0.4, < 4.1.0< 3.3.1

3.4.14.0.34.1.03.3.1

@backstage/plugin-scaffolder-backend

npm

< 4.1.0

4.1.0

Description

Impact

Patches

Patched in @backstage/plugin-scaffolder-backend version 4.1.0

Workarounds

Restrict Scaffolder task creation and task-read permissions to trusted users through the permission policy.
Limit who can register or modify templates and which Scaffolder actions may execute.
Run backend application files read-only outside a dedicated, least-privilege Scaffolder working directory.

References

Authorizing Scaffolder tasks, parameters, steps, and actions

NVD description