How severe is CVE-2026-106504?

CVE-2026-106504 has a CVSS score of 6.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-106504?

CVE-2026-106504 affects the following packages: @backstage/plugin-scaffolder-backend (npm). Ecosystems affected: npm.

How do I fix CVE-2026-106504?

Update @backstage/plugin-scaffolder-backend to 4.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-106504 is resolved across your whole dependency graph.

How do I detect CVE-2026-106504 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @backstage/plugin-scaffolder-backend, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-106504 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-106504 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-106504 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-106504?

CVE-2026-106504 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 16th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-106504?

CVE-2026-106504 is classified as CWE-532 (CWE-532). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-106504 published, and has it been updated?

CVE-2026-106504 was published on October 6, 2026 and was last updated on October 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

MEDIUM severity

CVE-2026-106504 — @backstage/plugin-scaffol…

MEDIUMFix: backstage/backstage@3eb3dc5

CVE-2026-106504 is a medium-severity (CVSS 6.5) CWE-532 vulnerability in @backstage/plugin-scaffolder-backend. A fix is available for @backstage/plugin-scaffolder-backend — see the affected versions and patch details below.

Backstage: Sensitive information exposure in scaffolder task logs

Also known asGHSA-4xvq-3m68-h444

Published

Oct 6, 2026

Updated

Oct 21, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-106504.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs16th percentile — riskier than 16% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-106504 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

69other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

@backstage/plugin-scaffolder-backendnpm

68Kdownloads / week

Description

Impact

An authenticated user who can create and read scaffolder tasks may be able to observe sensitive values in task logs in deployments with restrictive action permissions and affected templates. Exploitation requires a denied action whose input contains such a value.

Patches

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

Workarounds

Restrict scaffolder task creation and task-log reading to trusted users.
Avoid placing centrally managed sensitive values in inputs to actions that may be denied until upgrading.

References

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@backstage/plugin-scaffolder-backend`	all versions	4.1.0`npm install @backstage/plugin-scaffolder-backend@4.1.0`

Affected Products

2 products · 2 configurations

Application

backstagelinuxfoundation

< 1.54.6

range

Application

backstage\/plugin-scaffolder-backendlinuxfoundation

< 4.1.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @backstage/plugin-scaffolder-backend, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @backstage/plugin-scaffolder-backend to 4.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-106504 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

This vulnerability is rated as Moderate severity for Red Hat products because exploitation requires valid user authentication, permissions to create and inspect scaffolder tasks, and specific template configurations where an action containing sensitive data is denied by authorization policy. In typical deployments of…

Workaround published by Red Hat

To mitigate this issue, implement operational and access control restrictions: 1. Restrict scaffolder task creation and task log viewing permissions exclusively to trusted users through the application permission policy framework. 2. Review scaffolder templates to avoid passing sensitive credentials or secrets into inputs of actions that are subject to permission denials. Caveats: Restricting task creation and log inspection permissions limits self-service scaffolding capabilities for standard portal users.

Source: Red Hat security advisory for CVE-2026-106504 (CC BY 4.0)

Frequently Asked Questions

### Impact An authenticated user who can create and read scaffolder tasks may be able to observe sensitive values in task logs in deployments with restrictive action permissions and affected templates. Exploitation requires a denied action whose input contains such a value. ### Patches Patched in `@backstage/plugin-scaffolder-backend` version `4.1.0` ### Workarounds - Restrict scaffolder task creation and task-log reading to trusted users. - Avoid placing centrally managed sensitive values in inputs to actions that may be denied until upgrading. ### References - [Backstage threat model]