Vulnerability-Lookup

GHSA-472H-9C5J-PRRR

Vulnerability from github – Published: 2026-10-07 20:25 – Updated: 2026-10-07 20:25

Summary

Backstage: Inconsistent credential enforcement for overlapping proxy routes

Details

Impact

An operator can configure overlapping proxy paths with different credential requirements. When a parent path permits unauthenticated access and a nested path requires credentials, the parent exemption can also cover requests handled by the nested proxy. An unauthenticated caller may therefore reach the nested upstream through Backstage, including with static upstream credentials configured for that proxy.

Exploitation requires this specific overlapping route configuration. The resulting confidentiality and integrity impact depends on the capabilities exposed by the nested upstream.

Patches

Upgrade @backstage/plugin-proxy-backend to version 0.6.18 or later. The fixed package is available in Backstage v1.55.0.

Workarounds

Avoid nesting a credential-protected proxy path below a path configured with dangerously-allow-unauthenticated.
Apply the same credential requirement to overlapping proxy paths.
Restrict direct network access to the Backstage backend until the patched package is deployed.

Severity

4.8 (Medium)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Show details on source website

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@backstage/plugin-proxy-backend"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.5.0"
            },
            {
              "fixed": "0.6.18"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-106456"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-863"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-07T20:25:13Z",
    "nvd_published_at": "2026-10-06T21:17:15Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nAn operator can configure overlapping proxy paths with different credential requirements. When a parent path permits unauthenticated access and a nested path requires credentials, the parent exemption can also cover requests handled by the nested proxy. An unauthenticated caller may therefore reach the nested upstream through Backstage, including with static upstream credentials configured for that proxy.\n\nExploitation requires this specific overlapping route configuration. The resulting confidentiality and integrity impact depends on the capabilities exposed by the nested upstream.\n\n### Patches\n\nUpgrade `@backstage/plugin-proxy-backend` to version `0.6.18` or later. The fixed package is available in [Backstage v1.55.0](https://github.com/backstage/backstage/releases/tag/v1.55.0).\n\n### Workarounds\n\n- Avoid nesting a credential-protected proxy path below a path configured with `dangerously-allow-unauthenticated`.\n- Apply the same credential requirement to overlapping proxy paths.\n- Restrict direct network access to the Backstage backend until the patched package is deployed.",
  "id": "GHSA-472h-9c5j-prrr",
  "modified": "2026-10-07T20:25:13Z",
  "published": "2026-10-07T20:25:13Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/backstage/backstage/security/advisories/GHSA-472h-9c5j-prrr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-106456"
    },
    {
      "type": "WEB",
      "url": "https://github.com/backstage/backstage/commit/9df92923ac32558bb80edeceafd8de780c44e218"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/backstage/backstage"
    },
    {
      "type": "WEB",
      "url": "https://github.com/backstage/backstage/releases/tag/v1.55.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Backstage: Inconsistent credential enforcement for overlapping proxy routes"
}

CVE-2026-106456 (GCVE-0-2026-106456)

Vulnerability from cvelistv5 – Published: 2026-10-06 20:10 – Updated: 2026-10-07 18:24

Title

Backstage: Inconsistent credential enforcement for overlapping proxy routes

Summary

Backstage is an open framework for building developer portals. From 0.5.0 until 0.6.18, the @backstage/plugin-proxy-backend package is affected by inconsistent credential enforcement for overlapping proxy routes. An operator can configure overlapping proxy paths with different credential requirements. When a parent path permits unauthenticated access and a nested path requires credentials, the parent exemption can also cover requests handled by the nested proxy. An unauthenticated caller may therefore reach the nested upstream through Backstage, including with static upstream credentials configured for that proxy. This issue is fixed in version 0.6.18.

Severity

4.8 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-07 18:24 UTC

CWE

CWE-863 - Incorrect Authorization

Assigner

GitHub_M mitre root Scorecard

References

3 references

URL	Tags
https://github.com/backstage/backstage/security/a…	x_refsource_CONFIRM
https://github.com/backstage/backstage/commit/9df…	x_refsource_MISC
https://github.com/backstage/backstage/releases/t…	x_refsource_MISC

Impacted products

2 products

Vendor	Product	Version
backstage	backstage	Affected: >= 1.28.0, < 1.55.0
@backstage	plugin-proxy-backend	Affected: >= 0.5.0, < 0.6.18

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-106456",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-07T18:24:26.049704Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-07T18:24:34.406Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "backstage",
          "vendor": "backstage",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 1.28.0, \u003c 1.55.0"
            }
          ]
        },
        {
          "product": "plugin-proxy-backend",
          "vendor": "@backstage",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 0.5.0, \u003c 0.6.18"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Backstage is an open framework for building developer portals. From 0.5.0 until 0.6.18, the @backstage/plugin-proxy-backend package is affected by inconsistent credential enforcement for overlapping proxy routes. An operator can configure overlapping proxy paths with different credential requirements. When a parent path permits unauthenticated access and a nested path requires credentials, the parent exemption can also cover requests handled by the nested proxy. An unauthenticated caller may therefore reach the nested upstream through Backstage, including with static upstream credentials configured for that proxy. This issue is fixed in version 0.6.18."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 4.8,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-863",
              "description": "CWE-863: Incorrect Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-06T20:10:41.795Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/backstage/backstage/security/advisories/GHSA-472h-9c5j-prrr",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/backstage/backstage/security/advisories/GHSA-472h-9c5j-prrr"
        },
        {
          "name": "https://github.com/backstage/backstage/commit/9df92923ac32558bb80edeceafd8de780c44e218",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/backstage/backstage/commit/9df92923ac32558bb80edeceafd8de780c44e218"
        },
        {
          "name": "https://github.com/backstage/backstage/releases/tag/v1.55.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/backstage/backstage/releases/tag/v1.55.0"
        }
      ],
      "source": {
        "advisory": "GHSA-472h-9c5j-prrr",
        "discovery": "UNKNOWN"
      },
      "title": "Backstage: Inconsistent credential enforcement for overlapping proxy routes"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-106456",
    "datePublished": "2026-10-06T20:10:41.795Z",
    "dateReserved": "2026-10-06T16:49:40.591Z",
    "dateUpdated": "2026-10-07T18:24:34.406Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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