CVE-2026-106498: Backstage Improper URL Validation Vulnerability
HIGHCVE-2026-106498 is a HIGH (CVSS 7.7) improper url validation vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting Backstage libraries in the npm ecosystem. The issue involves improper url validation in catalog entity placeholder resolution. Remediation is available by upgrading affected packages to version 3.9.1.
CVE-2026-106498 at a Glance
Security Impact
CVSS: 7.7
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N).
How to Fix CVE-2026-106498
To remediate this vulnerability, upgrade all affected Backstage dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
npm install @backstage/plugin-catalog-backend@3.9.1Run the following command in your project directory to verify that all resolved dependencies use the patched release:
npm ls @backstage/plugin-catalog-backendHow to Check if You Are Affected
To determine whether your Node.js application is affected by CVE-2026-106498, inspect your project dependencies using npm:
npm ls @backstage/plugin-catalog-backendAnalyze the terminal output to locate any version of Backstage in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.9.1), your application is affected.
Note: The npm ls @backstage/plugin-catalog-backend command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-918: Server-Side Request Forgery (SSRF), where 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. In Backstage, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-106498 Affected Backstage Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
@backstage/plugin-catalog-backend
|
npm |
< 3.9.1
|
3.9.1
|
References
Frequently Asked Questions
What is CVE-2026-106498?
Which Backstage versions are affected?
What version fixes CVE-2026-106498?
Is @backstage/plugin-catalog-backend affected?
What is the CVSS score of CVE-2026-106498?
What CWE is associated with CVE-2026-106498?
How can I check npm dependencies for CVE-2026-106498?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-qgvj-qcf8-xq73",
"modified" : "2026-10-07T17:59:24Z",
"published" : "2026-10-07T17:59:24Z",
"aliases" : [ "CVE-2026-106498" ],
"summary" : "Backstage: Improper URL validation in catalog entity placeholder resolution",
"details" : "### Impact\n\nAn authenticated Backstage user could craft a catalog entity with placeholder directives that reference resources outside the entity's source repository. Under certain configurations, this could allow access to data not intended to be available to the user.\n\n### Patches\n\nPatched in `@backstage/plugin-catalog-backend` version `3.9.1`\n\n### Workarounds\n\nIf you're not able to update immediately:\n\n- Limit the scope of integration credentials (e.g., GitHub tokens) to only the repositories that Backstage needs to access.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "npm",
"name" : "@backstage/plugin-catalog-backend"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "3.9.1"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/security/advisories/GHSA-qgvj-qcf8-xq73"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-106498"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/commit/0b0f6fc89b4eb4872c76a498abbe1dc65998bb6e"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/commit/286bfc1f9cc3608a073b41016be302785be385d1"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/commit/61a10f19926aeda7f4a32de48d733e6710584634"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/commit/99729e925fd2bd40ba210022351a0ee6318e6197"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/commit/e786ac309ed2d775daf2309393c015c43902d6f6"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/backstage/backstage"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/releases/tag/v1.49.6"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/releases/tag/v1.50.5"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/releases/tag/v1.51.3"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/releases/tag/v1.53.2"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/releases/tag/v1.54.6"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-863", "CWE-918" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2026-10-07T17:59:24Z",
"nvd_published_at" : "2026-10-06T22:17:04Z"
}
}