Backstage: Scaffolder action input authorization bypass

{
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "cveMetadata": {
    "cveId": "CVE-2026-106503",
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "dateUpdated": "2026-10-06T21:37:33.675Z",
    "dateReserved": "2026-10-06T18:46:47.766Z",
    "datePublished": "2026-10-06T21:37:33.675Z",
    "state": "PUBLISHED"
  },
  "containers": {
    "cna": {
      "providerMetadata": {
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M",
        "dateUpdated": "2026-10-06T21:37:33.675Z"
      },
      "title": "Backstage: Scaffolder action input authorization bypass",
      "descriptions": [
        {
          "lang": "en",
          "value": "Backstage is an open framework for building developer portals. Prior to 3.3.1, 3.4.1, 4.0.3 and 4.1.0, the @backstage/plugin-scaffolder-backend package is affected by scaffolder action input authorization bypass. An authenticated user with access to affected Scaffolder templates could bypass configured action restrictions. Depending on integration credentials, this could grant unauthorized access to repositories and related source-control resources. This issue is fixed in versions 3.3.1, 3.4.1, 4.0.3 and 4.1.0."
        }
      ],
      "affected": [
        {
          "vendor": "backstage",
          "product": "backstage",
          "versions": [
            {
              "version": "< 1.49.6",
              "status": "affected"
            },
            {
              "version": ">= 1.50.0-next.0, < 1.50.5",
              "status": "affected"
            },
            {
              "version": ">= 1.51.0-next.0, < 1.54.6",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "@backstage",
          "product": "plugin-scaffolder-backend",
          "versions": [
            {
              "version": "< 3.3.1",
              "status": "affected"
            },
            {
              "version": ">= 3.4.0, < 3.4.1",
              "status": "affected"
            },
            {
              "version": ">= 4.0.0, < 4.0.3",
              "status": "affected"
            },
            {
              "version": ">= 4.0.4, < 4.1.0",
              "status": "affected"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "CWE-178: Improper Handling of Case Sensitivity",
              "cweId": "CWE-178",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "CWE-284: Improper Access Control",
              "cweId": "CWE-284",
              "type": "CWE"
            }
          ]
        }
      ],
      "references": [
        {
          "url": "https://github.com/backstage/backstage/security/advisories/GHSA-hmp2-4m7g-22cv",
          "name": "https://github.com/backstage/backstage/security/advisories/GHSA-hmp2-4m7g-22cv",
          "tags": [
            "x_refsource_CONFIRM"
          ]
        },
        {
          "url": "https://github.com/backstage/backstage/commit/11c1384c0649b8ab26391c6a4e4f34b80ab0d188",
          "name": "https://github.com/backstage/backstage/commit/11c1384c0649b8ab26391c6a4e4f34b80ab0d188",
          "tags": [
            "x_refsource_MISC"
          ]
        },
        {
          "url": "https://github.com/backstage/backstage/commit/a91ed72d540e80b62a73b39bb1563ff5018d52d1",
          "name": "https://github.com/backstage/backstage/commit/a91ed72d540e80b62a73b39bb1563ff5018d52d1",
          "tags": [
            "x_refsource_MISC"
          ]
        },
        {
          "url": "https://github.com/backstage/backstage/commit/e307e4f487103d815e484291b3fda778ab9983bf",
          "name": "https://github.com/backstage/backstage/commit/e307e4f487103d815e484291b3fda778ab9983bf",
          "tags": [
            "x_refsource_MISC"
          ]
        },
        {
          "url": "https://github.com/backstage/backstage/releases/tag/v1.49.6",
          "name": "https://github.com/backstage/backstage/releases/tag/v1.49.6",
          "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:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
            "attackVector": "NETWORK",
            "attackComplexity": "LOW",
            "privilegesRequired": "LOW",
            "userInteraction": "NONE",
            "scope": "UNCHANGED",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "availabilityImpact": "NONE",
            "baseScore": 8.1,
            "baseSeverity": "HIGH"
          }
        }
      ]
    }
  }
}