How severe is CVE-2026-106503?

CVE-2026-106503 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-106503 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-106503?

CVE-2026-106503 primarily affects Linuxfoundation Backstage/plugin-scaffolder-backend. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-106503?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-106503 published?

CVE-2026-106503 was published on 2026-10-06 and last updated on 2026-10-13.

CVE-2026-106503

CVE-2026-106503 is a high-severity vulnerability in Linuxfoundation Backstage/plugin-scaffolder-backend with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-178.

Key facts

Severity: High (CVSS 3.x base score 8.1)
EPSS exploit prediction: 0% (31st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-178
Affected product: Linuxfoundation Backstage/plugin-scaffolder-backend
Published: 2026-10-06
Last modified: 2026-10-13

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 scaffolder action input authorization bypass. An authenticated user with access to affected Scaffolder templates could bypass configured action restrictions. Depending on integration credentials, this could grant unauthorized access to repositories and related source-control resources. This issue is fixed in versions 3.3.1, 3.4.1, 4.0.3 and 4.1.0.

Frequently asked questions

What is CVE-2026-106503?: 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 scaffolder action input authorization bypass. An authenticated user with access to affected Scaffolder templates could bypass configured action restrictions. Depending on integration credentials, this could grant unauthorized access to repositories and related source-control resources. This issue is fixed in versions 3.3.1, 3.4.1, 4.0.3 and 4.1.0.
How severe is CVE-2026-106503?: CVE-2026-106503 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-106503 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-106503?: CVE-2026-106503 primarily affects Linuxfoundation Backstage/plugin-scaffolder-backend. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-106503?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-106503 published?: CVE-2026-106503 was published on 2026-10-06 and last updated on 2026-10-13.

References

Affected products (2)

cpe:2.3:a:linuxfoundation:backstage\/plugin-scaffolder-backend:*:*:*:*:*:*:*:*
cpe:2.3:a:linuxfoundation:backstage:*:*:*:*:*:*:*:*

More vulnerabilities in Linuxfoundation Backstage/plugin-scaffolder-backend

CVE-2026-106501 — Critical (CVSS 9.6): 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…
CVE-2026-106500 — High (CVSS 8.5): 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…
CVE-2026-106504 — Medium (CVSS 6.5): Backstage is an open framework for building developer portals. Prior to 4.1.0, the @backstage/plugin-scaffolder-backend…
CVE-2026-106462 — Medium (CVSS 6.4): Backstage is an open framework for building developer portals. Prior to 1.54.6, scaffolder source-control actions may…
CVE-2026-106506 — Medium (CVSS 5.3): Backstage is an open framework for building developer portals. Prior to 4.1.0, the @backstage/plugin-scaffolder-backend…
CVE-2026-106502 — Medium (CVSS 5.3): Backstage is an open framework for building developer portals. Prior to 4.1.0, the @backstage/plugin-scaffolder-backend…

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