Backstage has a Possible SSRF when reading from allowed URL's in `backend.reading.allow`
Summary
| CVE | CVE-2026-24048 |
|---|---|
| State | PUBLISHED |
| Assigner | GitHub_M |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-01-21 23:15:53 UTC |
| Updated | 2026-04-09 14:47:17 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v3.1 3.7 LOW from [email protected]
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
EPSS: 0.000370000 probability, percentile 0.113080000 (date 2026-04-09)
Problem Types: CWE-918 | CWE-918 CWE-918: Server-Side Request Forgery (SSRF)
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Primary | 3.7 | LOW | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N |
| 3.1 | [email protected] | Secondary | 3.5 | LOW | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N |
| 3.1 | CNA | DECLARED | 3.5 | LOW | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
HighPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
LowIntegrity
NoneAvailability
NoneCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Linuxfoundation | @backstage/backend Defaults | All | All | All | All |
| Application | Linuxfoundation | @backstage/backend Defaults | All | All | All | All |
| Application | Linuxfoundation | @backstage/backend Defaults | All | All | All | All |
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/backstage/backstage/security/advisories/GHSA-q2x5-4xjx-c6p9 | [email protected] | github.com | Vendor Advisory |
| github.com/backstage/backstage/commit/27f9061d24affd1b9212fe0abd476bfc3f... | [email protected] | github.com | Patch |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.