Backstage has XSS Vulnerability in Software Catalog

published 2023-02-14 3 y ago modified 2026-09-10 1 mo ago also GHSA-7hv8-3fr9-j2hv , EUVD-2023-0654

cvss: 6.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 39%
public exploits: 0; none known

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.

Patch / fix

fixed in 6 links 1

npm @backstage/core-components 0.12.4
npm @backstage/catalog-model 1.2.0
npm @backstage/plugin-catalog-backend 1.7.2
linuxfoundation backstage_catalog-model 1.2.0
linuxfoundation backstage_core-components 0.12.4
linuxfoundation backstage_plugin-catalog-backend 1.7.2

github.com/backstage/backstage@3d13719 commit

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 19 mo ago (2025-03-10)

Exploit prediction

0.45% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N
NVD	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
GitHub	3.1	6.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N

Affected packages

ecosystem	package	affected	fixed in
npm	@backstage/core-components	<0.12.4	0.12.4
npm	@backstage/catalog-model	<1.2.0	1.2.0
npm	@backstage/plugin-catalog-backend	<1.7.2	1.7.2

Affected products

backstage backstage

Classification

Weakness

CWE-84 Improper Neutralization of Encoded URI Schemes in a Web Page
CWE-79 Improper Neutralization of Input During Web Page Generation

References

github.com /backstage/backstage/commit/3d1371954512f7fa8bd0e2d357e00eada2c3e8a8
web, patch
github.com /backstage/backstage/security/advisories/GHSA-7hv8-3fr9-j2hv
web, vendor-advisory
nvd.nist.gov /vuln/detail/CVE-2023-25571
advisory
github.com /backstage/backstage
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary