CVE-2026-106500 backstage CVE debrief

Who should care

Defenders responsible for Backstage deployments, specifically those with Scaffolder tasks, should assess exposure and verify Scaffolder task permissions. Restricting task creation and read permissions to trusted users and ensuring backend application files are read-only outside a dedicated Scaffolder working directory can help mitigate the vulnerability.

Why it matters

CVE-2026-106500 Improper task state validation in Scaffolder backend affects Backstage. Authenticated users with Scaffolder task permissions may affect backend files under specific conditions, potentially compromising confidentiality, integrity, and availability.

• Verify Scaffolder task permissions to prevent unauthorized access
• Restrict task creation and read permissions to trusted users to limit potential impact
• Ensure backend application files are read-only outside a dedicated Scaffolder working directory to prevent file modifications
• Upgrade to `@backstage/plugin-scaffolder-backend` version `4.1.0` or later to apply patches

Technical summary

The vulnerability affects the `@backstage/plugin-scaffolder-backend` package. 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 vulnerability can be mitigated by verifying Scaffolder task permissions, restricting task creation and read permissions to trusted users, and ensuring backend application files are read-only outside a dedicated Scaffolder working directory.

Defensive priority

Defenders should prioritize verifying Scaffolder task permissions, restricting task creation and read permissions to trusted users, and ensuring backend application files are read-only outside a dedicated Scaffolder working directory.

Recommended defensive actions

• Verify Scaffolder task permissions and restrict task creation and read permissions to trusted users
• 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
• Upgrade to `@backstage/plugin-scaffolder-backend` version `4.1.0` or later
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The source corpus provides details on the vulnerability, patches, and workarounds. However, it does not provide information on exploitation, victims, or business impact. The vulnerability affects the `@backstage/plugin-scaffolder-backend` package. Defenders should verify Scaffolder task permissions, restrict task creation and read permissions to trusted users, and ensure backend application files are read-only outside a dedicated Scaffolder working directory.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.