CVE-2023-25571 in Backstage
Summary
by MITRE • 02/14/2023
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.
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Analysis
by VulDB Data Team • 03/16/2023
The vulnerability described in CVE-2023-25571 represents a critical cross-site scripting flaw within the Backstage developer portal platform, affecting multiple core components including backstage/catalog-model, backstage/core-components, and @backstage/plugin-catalog-backend. This vulnerability stems from insufficient input validation and sanitization mechanisms within the catalog system, specifically when processing entity data that may contain user-provided URLs. The flaw allows malicious actors with appropriate privileges to inject malicious script URLs into catalog entities, creating a persistent threat vector that can be exploited when legitimate users interact with these compromised entries.
The technical implementation of this vulnerability operates through the manipulation of catalog entity annotations where javascript: URLs can be embedded and subsequently executed when users click on links within the Backstage interface. This represents a classic XSS attack vector that leverages the trust relationship between the application and its users, where the platform itself becomes the conduit for malicious code execution. The vulnerability is particularly concerning because it requires only limited access to modify catalog content rather than full administrative privileges, making it exploitable by insiders or compromised accounts with catalog modification rights. The flaw is categorized under CWE-79 as Cross-site Scripting and aligns with ATT&CK technique T1566.001 for Phishing via Social Media and T1059.001 for Command and Scripting Interpreter.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform session hijacking, data exfiltration, and privilege escalation within the Backstage environment. When users navigate to malicious URLs within the catalog, the injected scripts can access the user's session cookies, potentially allowing unauthorized access to the Backstage platform. The vulnerability affects the entire Backstage ecosystem, as the compromised components are fundamental to the platform's catalog functionality, which is essential for developer portal operations. The patched versions implement multiple defensive measures including URL validation in the Link component, global window.open overrides, and enhanced annotation validation to prevent javascript: protocol usage in catalog metadata. These mitigations address both the frontend and backend layers of the application, providing comprehensive protection against this specific attack vector.
Security practitioners should implement the recommended mitigations including immediate upgrades to patched versions of all affected components, along with implementing strict access controls and code review processes for catalog modifications. The workaround of limiting access rights and requiring code reviews serves as an effective defense-in-depth strategy, as it reduces the attack surface by minimizing the number of users who can potentially introduce malicious content into the catalog system. Organizations should also consider implementing web application firewalls and content security policies to provide additional protection layers against similar vulnerabilities in the future. The vulnerability demonstrates the critical importance of input validation in web applications, particularly when dealing with user-generated content in enterprise platforms where trust relationships between users and applications are fundamental to the platform's security model.