Backstage catalog rules can be bypassed for URL locations using encoded path segments

[ Description ]Official 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.

[ Fixes ]Fixes and patches

• @backstage/plugin-catalog-backend 3.9.2Fixed version · GitHub Advisories · npm package @backstage/plugin-catalog-backend: upgrade to 3.9.2 or later (affected < 3.9.2)
• @backstage/plugin-catalog-backend 4.0.2Fixed version · GitHub Advisories · npm package @backstage/plugin-catalog-backend: upgrade to 4.0.2 or later (affected >= 4.0.0, < 4.0.2)

[ Packages ]Affected open-source packages

• @backstage/plugin-catalog-backend npmAffected < 3.9.2 · fixed in 3.9.2 · GHSA-w658-mh9p-ww8f
• @backstage/plugin-catalog-backend npmAffected >= 4.0.0, < 4.0.2 · fixed in 4.0.2 · GHSA-w658-mh9p-ww8f

[ References ]References

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