Vulnerability-Lookup

GHSA-9GHW-48H5-V2W5

Vulnerability from github – Published: 2026-10-07 17:59 – Updated: 2026-10-07 17:59

Summary

Backstage: Improper input validation in proxy-backend

Details

Impact

An authenticated Backstage user could craft a request URL that causes the proxy-backend to forward the request to a path outside the configured base path on the target server. This is limited to target servers already configured as proxy endpoints and requires Backstage authentication by default.

Patches

Patched in @backstage/plugin-proxy-backend version 0.6.17

Workarounds

Deploy a reverse proxy or WAF in front of Backstage that normalizes request paths before they reach the backend.

Severity

6.4 (Medium)


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

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JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@backstage/plugin-proxy-backend"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.6.17"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-106491"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20",
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-07T17:59:49Z",
    "nvd_published_at": "2026-10-06T21:17:18Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nAn authenticated Backstage user could craft a request URL that causes the proxy-backend to forward the request to a path outside the configured base path on the target server. This is limited to target servers already configured as proxy endpoints and requires Backstage authentication by default.\n\n### Patches\n\nPatched in `@backstage/plugin-proxy-backend` version `0.6.17`\n\n### Workarounds\n\n- Deploy a reverse proxy or WAF in front of Backstage that normalizes request paths before they reach the backend.",
  "id": "GHSA-9ghw-48h5-v2w5",
  "modified": "2026-10-07T17:59:49Z",
  "published": "2026-10-07T17:59:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/backstage/backstage/security/advisories/GHSA-9ghw-48h5-v2w5"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-106491"
    },
    {
      "type": "WEB",
      "url": "https://github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a41753c"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/backstage/backstage"
    },
    {
      "type": "WEB",
      "url": "https://github.com/backstage/backstage/releases/tag/v1.54.6"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Backstage: Improper input validation in proxy-backend"
}

CVE-2026-106491 (GCVE-0-2026-106491)

Vulnerability from cvelistv5 – Published: 2026-10-06 20:45 – Updated: 2026-10-07 17:52

Title

Backstage: Improper input validation in proxy-backend

Summary

Backstage is an open framework for building developer portals. Prior to 0.6.17, the @backstage/plugin-proxy-backend package is affected by improper input validation in proxy-backend. An authenticated Backstage user could craft a request URL that causes the proxy-backend to forward the request to a path outside the configured base path on the target server. This is limited to target servers already configured as proxy endpoints and requires Backstage authentication by default. This issue is fixed in version 0.6.17.

Severity

6.4 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/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 17:51 UTC

CWE

CWE-20 - Improper Input Validation
CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7580 records in the last 180 days details

References

3 references

URL	Tags
https://github.com/backstage/backstage/security/a…	x_refsource_CONFIRM
https://github.com/backstage/backstage/commit/233…	x_refsource_MISC
https://github.com/backstage/backstage/releases/t…	x_refsource_MISC

Impacted products

2 products

Vendor	Product	Version
backstage	backstage	Affected: < 1.54.6
@backstage	plugin-proxy-backend	Affected: < 0.6.17

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-106491",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-07T17:51:57.186407Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-07T17:52:11.914Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "backstage",
          "vendor": "backstage",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.54.6"
            }
          ]
        },
        {
          "product": "plugin-proxy-backend",
          "vendor": "@backstage",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.6.17"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Backstage is an open framework for building developer portals. Prior to 0.6.17, the @backstage/plugin-proxy-backend package is affected by improper input validation in proxy-backend. An authenticated Backstage user could craft a request URL that causes the proxy-backend to forward the request to a path outside the configured base path on the target server. This is limited to target servers already configured as proxy endpoints and requires Backstage authentication by default. This issue is fixed in version 0.6.17."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 6.4,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-20",
              "description": "CWE-20: Improper Input Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-22",
              "description": "CWE-22: Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-06T20:45:08.067Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/backstage/backstage/security/advisories/GHSA-9ghw-48h5-v2w5",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/backstage/backstage/security/advisories/GHSA-9ghw-48h5-v2w5"
        },
        {
          "name": "https://github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a41753c",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a41753c"
        },
        {
          "name": "https://github.com/backstage/backstage/releases/tag/v1.54.6",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/backstage/backstage/releases/tag/v1.54.6"
        }
      ],
      "source": {
        "advisory": "GHSA-9ghw-48h5-v2w5",
        "discovery": "UNKNOWN"
      },
      "title": "Backstage: Improper input validation in proxy-backend"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-106491",
    "datePublished": "2026-10-06T20:45:08.067Z",
    "dateReserved": "2026-10-06T18:46:47.766Z",
    "dateUpdated": "2026-10-07T17:52:11.914Z",
    "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.

Related by attack behaviour

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