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Fencer Vulns
high 8.1

CVE-2026-106503 json

Backstage: Scaffolder action input authorization bypass

published 2026-10-06 33 d ago modified 2026-10-13 26 d ago also GHSA-hmp2-4m7g-22cv , EUVD-2026-94068

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm @backstage/plugin-scaffolder-backend 3.3.1, 3.4.1, 4.0.3, 4.1.0
  • linuxfoundation backstage/plugin-scaffolder-backend 3.3.1, 3.4.1, 4.0.3, 4.1.0
  • linuxfoundation backstage 1.49.6, 1.50.5, 1.54.6

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-106503 updated cvss 8.1

plugin-scaffolder-backend: plugin-scaffolder-backend: Authorization bypass via scaffolder action inputs

  • Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9, rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend Red Hat Self-service automation portal 2 ansible-automation-platform/bootc-automation-portal-rhel9
    affected: workaround, no fix available
  • Red Hat Ansible Automation Platform 2.2 ansible-automation-platform/automation-portal 1792523640
    fixed: vendor fix RHSA-2026:86675

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
31 d ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
GitHub 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
npm @backstage/plugin-scaffolder-backend
<3.3.1
>=3.4.0, <3.4.1
>=4.0.0, <4.0.3
>=4.0.4, <4.1.0
3.3.1
3.4.1
4.0.3
4.1.0

Affected products

  • backstage backstage
  • @backstage plugin-scaffolder-backend

Classification

Weakness
  • CWE-178 Improper Handling of Case Sensitivity
  • CWE-284 Improper Access Control

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.