High severity · published Oct 6, 2026
CVE-2026-106500
Backstage: Improper task state validation in Scaffolder backend
8.5
CVSS
0.3%
EPSS
No
On KEV
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 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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 27% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BA
backstage · backstage
< 1.49.6; >= 1.50.0-next.0, < 1.50.5; >= 1.51.0-next.0, < 1.54.6 · source: vendor, NVD
PL
plugin-scaffolder-backend · @backstage
< 3.3.1; >= 3.4.0, < 3.4.1; >= 4.0.0, < 4.0.3; >= 4.0.4, < 4.1.0 · source: vendor
BA
Backstage/plugin-scaffolder-backend · Linuxfoundation
before 3.3.1; 3.4.0 before 3.4.1; 4.0.0 before 4.0.3; 4.0.4 before 4.1.0 · source: NVD