CVE-2026-66063: Goshs.de/goshs/v2 Path Traversal Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-wg2q-39h6-66x9",
  "modified" : "2026-07-28T22:10:01Z",
  "published" : "2026-07-28T22:08:53Z",
  "aliases" : [ "CVE-2026-66063" ],
  "summary" : "goshs has a Path Traversal issue",
  "details" : "## Summary\n\nThe multipart upload filename fix splits on the path separator but never rejects dot-dot, allowing a write outside the served tree.\n\n## Finding (Medium): upload filename escapes the served tree (residual of CVE-2026-35393)\n\nThe multipart filename fix (updown.go lines 135-136) splits on the path separator but never rejects \"..\". Uploading with filename=\"..\" results in os.Create against the parent of the upload folder with a trailing marker character, outside the served tree, and the subsequent failed rename leaves that file behind. Verified: a file containing ESCAPED_WRITE_PROOF was written outside the webroot, unauthenticated, with the default configuration. Not claimed: a Windows-specific variant (Go's Part.FileName() already applies filepath.Base).\n\n## Suggested fixes\n\n1. Reject any upload filename that is \"..\", is empty after sanitisation, or resolves outside the upload folder; validate the final resolved destination rather than only transforming the input.\n\n## Tooling\n\nAI assistance was used while investigating. The finding was reproduced against a running server on loopback.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "goshs.de/goshs/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.1.5-0.20260727065949-f3ef599e4091"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.1.4"
    }
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/patrickhener/goshs/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.1.5-0.20260727065949-f3ef599e4091"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.1.4"
    }
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "goshs.de/goshs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.1.4"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/patrickhener/goshs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.1.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/goshs-labs/goshs/security/advisories/GHSA-wg2q-39h6-66x9"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/goshs-labs/goshs/commit/f3ef599e409151d1380866e47de8b1afb0bb54fa"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/goshs-labs/goshs"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-28T22:08:53Z",
    "nvd_published_at" : null
  }
}