URL Manipulation Vulnerability in Backstage Developer Portal
CVE-2026-115923

6.5MEDIUM

Key Information:

Vendor

Backstage

Status
Backstage
Vendor
CVE Published:
26 October 2026

What is CVE-2026-115923?

A vulnerability exists in the Backstage developer portal where the DefaultCatalogRulesEnforcer incorrectly compares raw target URLs against specified catalog rules. Authenticated users with catalog.location.create permission can exploit this by using percent-encoded path segments, allowing untrusted URLs to match trusted patterns. This potentially admits dangerous entity content into the system. The issue affects versions prior to 3.9.2 and from 4.0.0 until 4.0.2, and it has been resolved in later updates.

Affected Version(s)

backstage < 3.9.2 < 3.9.2

backstage >= 4.0.0, < 4.0.2 < 4.0.0, 4.0.2

References

https://github.com/backstage/backstage/security/advisorie...
x_refsource_CONFIRM
https://github.com/backstage/backstage/commit/3214dc8f15d...
x_refsource_MISC
https://github.com/backstage/backstage/commit/737ff1c719d...
x_refsource_MISC

CVSS V3.1

Score:
6.5
Severity:
MEDIUM
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.