Description
Backstage is an open framework for building developer portals. Prior to 3.9.2 and from 4.0.0 until 4.0.2, DefaultCatalogRulesEnforcer in @backstage/plugin-catalog-backend compares the raw location.target URL against catalog.rules, while URL readers canonicalize the same URL before fetching it. An authenticated user with catalog.location.create permission can use percent-encoded path segments to make an untrusted URL match a trusted location pattern even though the canonical URL resolves outside that scope. This admits entity content from an untrusted source as trusted, while further downstream consequences depend on deployment configuration. This issue is fixed in versions 3.9.2 and 4.0.2.
Published: 2026-10-26
Score: 6.5 Medium
EPSS: n/a
KEV: No
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History

Mon, 26 Oct 2026 18:00:00 +0000

Type Values Removed Values Added
Description Backstage is an open framework for building developer portals. Prior to 3.9.2 and from 4.0.0 until 4.0.2, DefaultCatalogRulesEnforcer in @backstage/plugin-catalog-backend compares the raw location.target URL against catalog.rules, while URL readers canonicalize the same URL before fetching it. An authenticated user with catalog.location.create permission can use percent-encoded path segments to make an untrusted URL match a trusted location pattern even though the canonical URL resolves outside that scope. This admits entity content from an untrusted source as trusted, while further downstream consequences depend on deployment configuration. This issue is fixed in versions 3.9.2 and 4.0.2.
Title Backstage catalog rules can be bypassed for URL locations using encoded path segments
Weaknesses CWE-22
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-26T17:56:20.105Z

Reserved: 2026-10-23T20:21:45.107Z

Link: CVE-2026-115923

cve-icon Vulnrichment

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cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-26T18:17:40.360

Modified: 2026-10-26T18:39:42.503

Link: CVE-2026-115923

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses