Backstage up to 0.12.1/0.13.1/0.14.0 Request Header server-side request forgery

Summaryinfo

A vulnerability marked as critical has been reported in Backstage up to 0.12.1/0.13.1/0.14.0. Affected by this issue is some unknown functionality of the component Request Header Handler. Performing a manipulation results in server-side request forgery. This vulnerability is known as CVE-2026-24048. Remote exploitation of the attack is possible. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Backstage up to 0.12.1/0.13.1/0.14.0. This affects an unknown code of the component Request Header Handler. The manipulation with an unknown input leads to a server-side request forgery vulnerability. CWE is classifying the issue as CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. This is going to have an impact on confidentiality. The summary by CVE is:

Backstage is an open framework for building developer portals, and @backstage/backend-defaults provides the default implementations and setup for a standard Backstage backend app. Prior to versions 0.12.2, 0.13.2, 0.14.1, and 0.15.0, 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. 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. Some workarounds are available. 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, and/or use network-level controls to block access from Backstage to sensitive internal endpoints.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-24048 since 01/20/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 0.12.2, 0.13.2 or 0.14.1 eliminates this vulnerability. Applying the patch 27f9061d24affd1b9212fe0abd476bfc3fbaedcb is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Name

• Backstage

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.12.0
• 0.12.1
• 0.13
• 0.13.0
• 0.13.1
• 0.14.0

License

• open-source

Website

• Product: https://github.com/backstage/backstage/

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