CVE-2026-115923

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.

• CWE-22

• https://github.com/backstage/backstage/commit/3214dc8f15d4a08a2fd07a72a8fe4d00aeac0db4
• https://github.com/backstage/backstage/commit/737ff1c719dbd5a97f375b7f1db6d61416618419
• https://github.com/backstage/backstage/releases/tag/v1.54.10
• https://github.com/backstage/backstage/releases/tag/v1.56.1
• https://github.com/backstage/backstage/security/advisories/GHSA-w658-mh9p-ww8f

Published

Oct 26, 2026

Last Modified

Oct 26, 2026

Status

Awaiting Analysis

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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