CVE-2026-106510: Backstage Remote Code Execution Vulnerability

HIGH
Advisory Identifier: GHSA-4488-j8vj-vqqv
Share
CVSS 7.7
CWE-183 CWE-470
Published
Advisory Summary

CVE-2026-106510 is a HIGH (CVSS 7.7) remote code execution vulnerability (CWE-183: Permissive List of Allowed Inputs) affecting Backstage libraries in the npm ecosystem. The issue involves remote code execution via crafted markdown_extensions in techdocs mkdocs.yml. Remediation is available by upgrading affected packages to version 1.15.4.

CVE-2026-106510 at a Glance

CVE Identifier CVE-2026-106510
GHSA Identifier GHSA-4488-j8vj-vqqv
Severity HIGH
CVSS v3.1 Base Score 7.7
CWE Classification CWE-183: Permissive List of Allowed Inputs
Affected Product Backstage
Package Ecosystem npm
Published Date
Last Updated

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:H/PR:L/UI:N/S:C/C:H/I:L/A:L).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity Low (I:L)
Availability Low (A:L)

How to Fix CVE-2026-106510

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.

@backstage/plugin-techdocs-node fixed: 1.15.4 
npm install @backstage/plugin-techdocs-node@1.15.4
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls @backstage/plugin-techdocs-node

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-106510, inspect your project dependencies using npm:

npm ls @backstage/plugin-techdocs-node

Analyze 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 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-183: Permissive List of Allowed Inputs, where the product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are explicitly allowed by policy because the inputs are assumed to be safe, but the list is too permissive - that is, it allows an input that is unsafe, leading to resultant weaknesses. 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

### Impact An authenticated user who can register catalog entities can provide a crafted `mkdocs.yml` causing arbitrary OS command execution on the TechDocs build host when the docs are built. ### Patches Patched in `@backstage/plugin-techdocs-node`, version `1.15.4`. ### Workarounds If you cannot upgrade immediately: - Switch to `techdocs.builder: external` to isolate TechDocs builds in a container. - Restrict who can register catalog entities with TechDocs annotations. - Audit existing catalog entities for suspicious `markdown_extensions` values in their `mkdocs.yml` files.

CVE-2026-106510 Affected Backstage Versions

1 component(s)
Fixed Versions:
1.15.4
Product / Package Ecosystem Affected Versions Fixed Version
@backstage/plugin-techdocs-node
npm/@backstage/plugin-techdocs-node
npm
< 1.15.4
1.15.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/backstage/backstage/security/advisories/GHSA-4488-j8vj-vqqv
NVD — CVE-2026-106510 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-106510
Security Fix Commit FIX COMMIT
https://github.com/backstage/backstage/commit/02cd7cdbb18b687446277b5602adaee7f1d53cbb
Security Fix Commit FIX COMMIT
https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9d
Backstage Source Repository REPOSITORY
https://github.com/backstage/backstage
Backstage Release RELEASE
https://github.com/backstage/backstage/releases/tag/v1.50.5
Backstage Release RELEASE
https://github.com/backstage/backstage/releases/tag/v1.54.6

Frequently Asked Questions

What is CVE-2026-106510?
CVE-2026-106510 is a security vulnerability in Backstage involving Remote code execution via crafted markdown_extensions in TechDocs mkdocs.yml under CWE-183: Permissive List of Allowed Inputs.
Which Backstage versions are affected?
Affected versions include releases prior to 1.15.4 across affected packages: @backstage/plugin-techdocs-node.
What version fixes CVE-2026-106510?
Upgrading to 1.15.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @backstage/plugin-techdocs-node affected?
Yes, @backstage/plugin-techdocs-node is affected in releases prior to 1.15.4. Upgrade your dependency to 1.15.4 or later.
What is the CVSS score of CVE-2026-106510?
CVE-2026-106510 has a CVSS v3.1 base score of 7.7 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L.
What CWE is associated with CVE-2026-106510?
CVE-2026-106510 is classified under CWE-183: Permissive List of Allowed Inputs (The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are explicitly allowed by policy because the inputs are assumed to be safe, but the list is too permissive - that is, it allows an input that is unsafe, leading to resultant weaknesses.).
How can I check npm dependencies for CVE-2026-106510?
Run the dependency tree command: 'npm ls @backstage/plugin-techdocs-node'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4488-j8vj-vqqv",
  "modified" : "2026-10-07T18:03:22Z",
  "published" : "2026-10-07T18:03:22Z",
  "aliases" : [ "CVE-2026-106510" ],
  "summary" : "Backstage: Remote code execution via crafted markdown_extensions in TechDocs mkdocs.yml",
  "details" : "### Impact\n\nAn authenticated user who can register catalog entities can provide a crafted `mkdocs.yml` causing arbitrary OS command execution on the TechDocs build host when the docs are built.\n\n### Patches\n\nPatched in `@backstage/plugin-techdocs-node`, version `1.15.4`.\n\n### Workarounds\n\nIf you cannot upgrade immediately:\n\n- Switch to `techdocs.builder: external` to isolate TechDocs builds in a container.\n- Restrict who can register catalog entities with TechDocs annotations.\n- Audit existing catalog entities for suspicious `markdown_extensions` values in their `mkdocs.yml` files.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L"
  } ],
  "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-4488-j8vj-vqqv"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-106510"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/commit/02cd7cdbb18b687446277b5602adaee7f1d53cbb"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9d"
  }, {
    "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-183", "CWE-470" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-07T18:03:22Z",
    "nvd_published_at" : "2026-10-07T15:17:12Z"
  }
}