GHSA-q2x5-4xjx-c6p9 Backstage has a Possible SSRF when reading from allowed URL's in `backend.reading.allow`

• npm @backstage/backend-defaults: < 0.12.2 → fixed in 0.12.2 • npm @backstage/backend-defaults: >= 0.13.0, < 0.13.2 → fixed in 0.13.2 • npm @backstage/backend-defaults: >= 0.14.0, < 0.14.1 → fixed in 0.14.1

Impact The `FetchUrlReader` component, used by the catalog and other plugins to fetch content from URLs, followed HTTP redirects automatically. This allowed an attacker who controls a host listed in `backend.reading.allow` to redirect requests to internal or sensitive URLs that are not on the allowlist, bypassing the URL allowlist security control. This is a Server-Side Request Forgery (SSRF) vulnerability that could allow access to internal resources, but it does not allow attackers to include additional request headers. Patches This vulnerability is fixed in `@backstage/backend-defaults` version 0.12.2, 0.13.2, 0.14.1, and 0.15.0. Users should upgrade to this version or later. Workarounds • Restrict `backend.reading.allow` to only trusted hosts that you control and that do not issue redirects • Ensure allowed hosts do not have open redirect vulnerabilities • Use network-level controls to block access from Backstage to sensitive internal endpoints References • OWASP SSRF Prevention Cheat Sheet