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Fencer Intel
medium 4.3

CVE-2026-106495 json

Backstage: Improper access control in backend action invocation

published 28d ago modified 24d ago also EUVD-2026-97833 , GHSA-3xr5-8w6c-p5gw

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 14%
public exploits
0
none known

Summary

Backstage is an open framework for building developer portals. Prior to 0.17.8, the @backstage/backend-defaults package is affected by improper access control in backend action invocation. An authenticated user could invoke actions that an operator had excluded through action configuration. Existing action permissions and downstream authorization remain enforced. This issue is fixed in version 0.17.8.

Patch / fix

  • npm @backstage/backend-defaults 0.17.8
  • linuxfoundation backstage/backend_defaults 0.17.8
  • linuxfoundation backstage 0.17.8, 1.54.6
  • linuxfoundation backstage/backend-defaults 0.17.8
  • linuxfoundation @backstage/techdocs-common 1.54.6
  • linuxfoundation backstage_core-components 1.54.6
  • linuxfoundation backstage_catalog-model 1.54.6
  • linuxfoundation backstage_plugin-catalog-backend 1.54.6
  • linuxfoundation @backstage/plugin-techdocs 1.54.6
  • linuxfoundation auth_backend 1.54.6

Is CVE-2026-106495 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.

Check with Fencer

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-2026-106495 updated cvss 4.3

backend-defaults: Backstage: Unauthorized execution of excluded actions via improper access control

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

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
partial
Assessed
27d ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
GitHub 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm @backstage/backend-defaults
<0.17.8
0.17.8

Affected products

  • backstage backstage
  • @backstage backend-defaults

Classification

Weakness

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.