Backstage has improper input validation in TechDocs Markdown extension configuration

{
  "id": "4e800500ad94e2e7a3045eec5ef7b1c49180d10333c7c29d58237f1284794e47",
  "url": "https://osv.dev/vulnerability/GHSA-f7v3-xhm6-w245",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Backstage has improper input validation in TechDocs Markdown extension configuration",
    "summary": "### Impact An 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. ### Patches Patched in `@backstage/plugin-techdocs-node` version `1.15.4`. Adopters 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. ### Workarounds - Generate TechDocs only from trusted repositories with reviewed MkDocs configuration. - Use isolated build environments with restricted filesystem access and network egress. - Prefer externally generated TechDocs with appropriately sandboxed CI.",
    "evidence": "osv:GHSA-f7v3-xhm6-w245",
    "products": [
      {
        "name": {
          "value": "@backstage/plugin-techdocs-node",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.15.4",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-f7v3-xhm6-w245",
      "aliases": [
        "CVE-2026-106557",
        "GHSA-f7v3-xhm6-w245"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.15.4"
                }
              ]
            }
          ],
          "package": {
            "name": "@backstage/plugin-techdocs-node",
            "purl": "pkg:npm/%40backstage/plugin-techdocs-node",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-f7v3-xhm6-w245/GHSA-f7v3-xhm6-w245.json"
          }
        }
      ],
      "modified": "2026-10-07T16:30:06.348764958Z",
      "provider": "osv",
      "references": [
        "https://github.com/backstage/backstage/security/advisories/GHSA-f7v3-xhm6-w245",
        "https://github.com/backstage/backstage/commit/017ace52d9b327ededc6704cf17799c875ae0f29",
        "https://github.com/backstage/backstage/commit/2d9de4ca117a529de4b6ed7dfb7aa507ca7b3f91",
        "https://github.com/backstage/backstage",
        "https://github.com/backstage/backstage/releases/tag/v1.50.5",
        "https://github.com/backstage/backstage/releases/tag/v1.54.6"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-22",
          "CWE-918"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-07T16:22:58Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-106557",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 95167,
  "published_at": "2026-10-07T16:22:58+00:00"
}