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Fencer Intel
high 8.5

CVE-2026-106500 json

Backstage: Improper task state validation in Scaffolder backend

published last mo. modified 27d ago also EUVD-2026-94058 , GHSA-xvgh-hmx8-9xxf

cvss
8.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 27%
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 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.

Patch / fix

  • npm @backstage/plugin-scaffolder-backend 4.1.0
  • linuxfoundation @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_plugin-scaffolder-backend 3.3.1, 3.4.1, 4.0.3, 4.1.0

Is CVE-2026-106500 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2026-106500 updated cvss 7.1

@backstage/plugin-scaffolder-backend: @backstage/plugin-scaffolder-backend: Unauthorized file manipulation via improper task state validation

  • 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/automation-portal, ansible-automation-platform/bootc-automation-portal-rhel9
    affected: workaround, no fix available

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
last mo.

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 8.5 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
GitHub 3.1 8.5 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
npm @backstage/plugin-scaffolder-backend
<4.1.0
4.1.0

Affected products

  • backstage backstage
  • @backstage plugin-scaffolder-backend

Classification

Weakness
  • CWE-59 Improper Link Resolution Before File Access
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization

References

Sources

Fencer Intel 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.