CVE intelligence and bounded remediation

CVE-2023-25571 — Backstage is an open platform for building developer portals

Medium CVSS 6.8

Backstage is an open platform for building developer portals. `@backstage/catalog-model` prior to version 1.2.0, `@backstage/core-components` prior to 0.12.4, and `@backstage/plugin-catalog-backend` prior to 1.7.2 are affected by a cross-site scripting vulnerability. This vulnerability allows a malicious actor with access to add or modify content in an instance of the Backstage software catalog to inject script URLs in the entities stored in the catalog. If users of the catalog then click on said URLs, that can lead to an XSS attack. This vulnerability has been patched in both the frontend and backend implementations. The default `Link` component from `@backstage/core-components` version 1.2.0 and greater will now reject `javascript:` URLs, and there is a global override of `window.open` to do the same. In addition, the catalog model v0.12.4 and greater as well as the catalog backend v1.7.2 and greater now has additional validation built in that prevents `javascript:` URLs in known annotations. As a workaround, the general practice of limiting access to modifying catalog content and requiring code reviews greatly help mitigate this vulnerability.

Severity
Medium
CVSS
6.8 (3.1)
Published
2023-02-14
CISA KEV
Not currently listed
Ecosystem
javascript/npm
Weaknesses
CWE-79, CWE-84

Affected products

  • linuxfoundation / backstage_catalog-model
  • linuxfoundation / backstage_core-components
  • linuxfoundation / backstage_plugin-catalog-backend

Matched remediation archetype

Cross-site scripting and unsafe browser output

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Check exposure

  • Trace reflected, stored, and DOM-derived untrusted values into HTML, attributes, URLs, styles, scripts, and client-side template sinks.
  • Identify affected origins, authenticated user roles, sensitive browser capabilities, and where content is shared across tenants.
  • Review framework escaping, rich-text sanitization, legacy templates, and client-side rendering paths.

Remediate safely

  • Use context-aware framework output encoding and safe DOM APIs; keep untrusted data out of executable contexts.
  • Sanitize intentionally supported markup with a maintained allowlist policy and validate URLs and attributes separately.
  • Update affected rendering components and add tests for every output context using inert sentinel markup.

Authoritative sources

Complete CVE record and remediation plan

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