CVE-2026-56857 (GCVE-0-2026-56857)

Vulnerability from cvelistv5 – Published: 2026-10-08 22:53 – Updated: 2026-10-08 22:53
VLAI
Title
Root.Mkdir(All) can follow junctions out of the root on Windows in os
Summary
On Windows, when the target of Root.Mkdir or Root.MkdirAll is a junction pointing to an empty location, the operation can create a directory at the junction target even when that target is located outside the root. This only applies to operations where the last path component is a junction (path/to/junction, but not path/junction/target).
Severity
No CVSS data available.
CWE
  • CWE-1386 - Insecure Operation on Windows Junction / Mount Point
Assigner
Go CNA under the Google root
CNA scorecard E 42/100 over 75 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Go standard library os Affected: 0 , < 1.26.9 (semver)
Affected: 1.27.0-0 , < 1.27.2 (semver)
guessed Create a notification for this product.
Go standard library internal/syscall/windows Affected: 0 , < 1.26.9 (semver)
Affected: 1.27.0-0 , < 1.27.2 (semver)
guessed Create a notification for this product.
Credits
Daniele Ballarini
Show details on NVD website
To clipboard 

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            {
              "name": "Root.Mkdir"
            },
            {
              "name": "doInRoot"
            },
            {
              "name": "rootMkdirAll"
            },
            {
              "name": "Root.Chmod"
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            {
              "name": "Root.Chown"
            },
            {
              "name": "Root.Chtimes"
            },
            {
              "name": "Root.Lchown"
            },
            {
              "name": "Root.Link"
            },
            {
              "name": "Root.MkdirAll"
            },
            {
              "name": "Root.Remove"
            },
            {
              "name": "Root.RemoveAll"
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            {
              "name": "Root.Rename"
            },
            {
              "name": "Root.Symlink"
            }
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              "versionType": "semver"
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              "versionType": "semver"
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          ]
        }
      ],
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          "value": "Daniele Ballarini"
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      "descriptions": [
        {
          "lang": "en",
          "value": "On Windows, when the target of Root.Mkdir or Root.MkdirAll is a junction pointing to an empty location, the operation can create a directory at the junction target even when that target is located outside the root. This only applies to operations where the last path component is a junction (path/to/junction, but not path/junction/target)."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-1386: Insecure Operation on Windows Junction / Mount Point",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-08T22:53:58.387Z",
        "orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
        "shortName": "Go"
      },
      "references": [
        {
          "url": "https://go.dev/cl/847305"
        },
        {
          "url": "https://go.dev/issue/81739"
        },
        {
          "url": "https://groups.google.com/g/golang-announce/c/U2fTuyDJznI"
        },
        {
          "url": "https://pkg.go.dev/vuln/GO-2026-6604"
        }
      ],
      "title": "Root.Mkdir(All) can follow junctions out of the root on Windows in os"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
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    "cveId": "CVE-2026-56857",
    "datePublished": "2026-10-08T22:53:58.387Z",
    "dateReserved": "2026-06-23T15:10:49.353Z",
    "dateUpdated": "2026-10-08T22:53:58.387Z",
    "state": "PUBLISHED"
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                "defaultStatus": "unaffected",
                "packageName": "os",
                "platforms": [
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                "programRoutines": [
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                  {
                    "name": "doInRoot"
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                  {
                    "name": "rootMkdirAll"
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                  {
                    "name": "Root.Chmod"
                  },
                  {
                    "name": "Root.Chown"
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                  {
                    "name": "Root.Chtimes"
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                  },
                  {
                    "name": "Root.Link"
                  },
                  {
                    "name": "Root.MkdirAll"
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                  {
                    "name": "Root.Remove"
                  },
                  {
                    "name": "Root.RemoveAll"
                  },
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                    "name": "Root.Rename"
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                    "version": "0",
                    "versionType": "semver"
                  },
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                    "lessThan": "1.27.2",
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                    "versionType": "semver"
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                    "status": "affected",
                    "version": "1.27.0-0",
                    "versionType": "semver"
                  }
                ]
              }
            ],
            "source": "security@golang.org"
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        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "On Windows, when the target of Root.Mkdir or Root.MkdirAll is a junction pointing to an empty location, the operation can create a directory at the junction target even when that target is located outside the root. This only applies to operations where the last path component is a junction (path/to/junction, but not path/junction/target)."
          }
        ],
        "id": "CVE-2026-56857",
        "lastModified": "2026-10-08T23:17:01.487",
        "metrics": {},
        "published": "2026-10-08T23:17:01.487",
        "references": [
          {
            "source": "security@golang.org",
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            "url": "https://go.dev/issue/81739"
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          }
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        "sourceIdentifier": "security@golang.org",
        "vulnStatus": "Received"
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    "redhat_vex": {
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      "current_release_date": "2026-10-08T23:59:05+00:00",
      "cve": "CVE-2026-56857",
      "id": "CVE-2026-56857",
      "initial_release_date": "2026-10-08T22:53:58.387000+00:00",
      "product_status:known_affected": "178",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "os: golang: golang: Directory traversal via Windows junction handling",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-56857.json",
      "version": "3"
    }
  }
}



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