GHSA-WG2Q-39H6-66X9

Vulnerability from github – Published: 2026-07-28 22:08 – Updated: 2026-07-28 22:10
VLAI
Summary
goshs has a Path Traversal issue
Details

Summary

The multipart upload filename fix splits on the path separator but never rejects dot-dot, allowing a write outside the served tree.

Finding (Medium): upload filename escapes the served tree (residual of CVE-2026-35393)

The 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).

Suggested fixes

  1. 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.

Tooling

AI assistance was used while investigating. The finding was reproduced against a running server on loopback.

Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Show details on source website
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.1.4"
      },
      "package": {
        "ecosystem": "Go",
        "name": "goshs.de/goshs/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.1.5-0.20260727065949-f3ef599e4091"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.1.4"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/patrickhener/goshs/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.1.5-0.20260727065949-f3ef599e4091"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "goshs.de/goshs"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "1.1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/patrickhener/goshs"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "1.1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-66063"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-28T22:08:53Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "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\u0027s 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.",
  "id": "GHSA-wg2q-39h6-66x9",
  "modified": "2026-07-28T22:10:01Z",
  "published": "2026-07-28T22:08:53Z",
  "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "goshs has a Path Traversal issue"
}



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