CVE-2026-106557: @backstage/plugin techdocs node Backstage Has Improper Input Validation Vulnerability
HIGHCVE-2026-106557 is a HIGH (CVSS 7.7) backstage has improper input validation vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting @backstage/plugin techdocs node libraries in the npm ecosystem. The issue involves backstage has improper input validation in techdocs markdown extension configuration. Remediation is available by upgrading affected packages to version 1.15.4.
CVE-2026-106557 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-2026-106557
To remediate this vulnerability, upgrade all affected @backstage/plugin techdocs node 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-techdocs-node@1.15.4Run the following command in your project directory to verify that all resolved dependencies use the patched release:
npm ls @backstage/plugin-techdocs-nodeHow to Check if You Are Affected
To determine whether your Node.js application is affected by CVE-2026-106557, inspect your project dependencies using npm:
npm ls @backstage/plugin-techdocs-nodeAnalyze the terminal output to locate any version of @backstage/plugin techdocs node in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.15.4), your application is affected.
Note: The npm ls @backstage/plugin-techdocs-node 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/plugin techdocs node, 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-2026-106557 Affected @backstage/plugin techdocs node Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
@backstage/plugin-techdocs-node
|
npm |
< 1.15.4
|
1.15.4
|
References
Frequently Asked Questions
What is CVE-2026-106557?
Which @backstage/plugin techdocs node versions are affected?
What version fixes CVE-2026-106557?
Is @backstage/plugin-techdocs-node affected?
What is the CVSS score of CVE-2026-106557?
What CWE is associated with CVE-2026-106557?
How can I check npm dependencies for CVE-2026-106557?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-f7v3-xhm6-w245",
"modified" : "2026-10-07T16:22:58Z",
"published" : "2026-10-07T16:22:58Z",
"aliases" : [ "CVE-2026-106557" ],
"summary" : "Backstage has improper input validation in TechDocs Markdown extension configuration",
"details" : "### Impact\n\nAn authenticated user who can register or modify documentation sources may cause a TechDocs build to access resources outside the intended documentation boundary. Depending on deployment configuration, this may expose sensitive backend-host data or internal network resources.\n\n### Patches\n\nPatched in `@backstage/plugin-techdocs-node` version `1.15.4`.\n\nAdopters must also use `pymdown-extensions` version `10.21.3` or newer, normally through `mkdocs-techdocs-core` version `1.7.0` or newer. `@backstage/plugin-techdocs-node` does not control the Python dependencies used by the generator; with an older PyMdown release, snippets may remain vulnerable to file inclusion even after their configuration is sanitized.\n\n### Workarounds\n\n- Generate TechDocs only from trusted repositories with reviewed MkDocs configuration.\n- Use isolated build environments with restricted filesystem access and network egress.\n- Prefer externally generated TechDocs with appropriately sandboxed CI.",
"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-techdocs-node"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "1.15.4"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/security/advisories/GHSA-f7v3-xhm6-w245"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/commit/017ace52d9b327ededc6704cf17799c875ae0f29"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/commit/2d9de4ca117a529de4b6ed7dfb7aa507ca7b3f91"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/backstage/backstage"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/releases/tag/v1.50.5"
}, {
"type" : "WEB",
"url" : "https://github.com/backstage/backstage/releases/tag/v1.54.6"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-22", "CWE-918" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2026-10-07T16:22:58Z",
"nvd_published_at" : null
}
}