Backstage: Improper validation of MkDocs theme configuration in TechDocs

{
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "cveMetadata": {
    "cveId": "CVE-2026-106509",
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "dateUpdated": "2026-10-06T21:50:07.721Z",
    "dateReserved": "2026-10-06T18:46:47.767Z",
    "datePublished": "2026-10-06T21:50:07.721Z",
    "state": "PUBLISHED"
  },
  "containers": {
    "cna": {
      "providerMetadata": {
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M",
        "dateUpdated": "2026-10-06T21:50:07.721Z"
      },
      "title": "Backstage: Improper validation of MkDocs theme configuration in TechDocs",
      "descriptions": [
        {
          "lang": "en",
          "value": "Backstage is an open framework for building developer portals. Prior to 1.14.6, the @backstage/plugin-techdocs-node package is affected by improper validation of mkdocs theme configuration in techdocs. When TechDocs is configured to build documentation locally or in a container, a user with write access to a registered repository can include configuration values in mkdocs.yml that cause arbitrary code execution during the documentation build process. This issue is fixed in versions 1.14.6 and 1.15.4."
        }
      ],
      "affected": [
        {
          "vendor": "backstage",
          "product": "backstage",
          "versions": [
            {
              "version": "< 1.50.5",
              "status": "affected"
            },
            {
              "version": ">= 1.51.0-next.0, < 1.54.6",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "@backstage",
          "product": "plugin-techdocs-node",
          "versions": [
            {
              "version": "< 1.14.6",
              "status": "affected"
            },
            {
              "version": ">= 1.15.0, < 1.15.4",
              "status": "affected"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "CWE-94: Improper Control of Generation of Code ('Code Injection')",
              "cweId": "CWE-94",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine",
              "cweId": "CWE-1336",
              "type": "CWE"
            }
          ]
        }
      ],
      "references": [
        {
          "url": "https://github.com/backstage/backstage/security/advisories/GHSA-8w7q-29mw-gf5c",
          "name": "https://github.com/backstage/backstage/security/advisories/GHSA-8w7q-29mw-gf5c",
          "tags": [
            "x_refsource_CONFIRM"
          ]
        },
        {
          "url": "https://github.com/backstage/backstage/commit/02cd7cdbb18b687446277b5602adaee7f1d53cbb",
          "name": "https://github.com/backstage/backstage/commit/02cd7cdbb18b687446277b5602adaee7f1d53cbb",
          "tags": [
            "x_refsource_MISC"
          ]
        },
        {
          "url": "https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9d",
          "name": "https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9d",
          "tags": [
            "x_refsource_MISC"
          ]
        },
        {
          "url": "https://github.com/backstage/backstage/releases/tag/v1.50.5",
          "name": "https://github.com/backstage/backstage/releases/tag/v1.50.5",
          "tags": [
            "x_refsource_MISC"
          ]
        },
        {
          "url": "https://github.com/backstage/backstage/releases/tag/v1.54.6",
          "name": "https://github.com/backstage/backstage/releases/tag/v1.54.6",
          "tags": [
            "x_refsource_MISC"
          ]
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "version": "3.1",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L",
            "attackVector": "NETWORK",
            "attackComplexity": "HIGH",
            "privilegesRequired": "LOW",
            "userInteraction": "NONE",
            "scope": "CHANGED",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "LOW",
            "availabilityImpact": "LOW",
            "baseScore": 7.7,
            "baseSeverity": "HIGH"
          }
        }
      ]
    }
  }
}