{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.17.8"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "f7162c178fdcbe4b2a51efcbb07888e499ce3e95"
            }
          ],
          "repo": "https://github.com/xyproto/algernon",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-jc3j-x6pg-4hmv"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-22",
      "CWE-23",
      "CWE-644"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48126.json"
  },
  "details": "Algernon is a small self-contained pure-Go web server. Prior to 1.17.8, when algernon is started with --domain (or --letsencrypt, which silently turns on --domain at engine/flags.go:372), the request handler resolves the served directory by joining the configured --dir with the value of the client-supplied Host header. The join is performed by filepath.Join with no validation, so a Host: .. header walks one level above the document root. Subsequent file resolution then exposes everything in that parent directory — arbitrary file read, full directory listing, and, if any .lua file is present, server-side Lua execution. This vulnerability is fixed in 1.17.8.",
  "id": "CVE-2026-48126",
  "modified": "2026-08-12T03:51:31.191065070Z",
  "published": "2026-05-26T16:44:09.104Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48126.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/xyproto/algernon/security/advisories/GHSA-jc3j-x6pg-4hmv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-48126"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Algernon: Host header path traversal in --domain mode reads files and runs Lua from parent dir"
}