Vulnerability-Lookup

GHSA-4MH3-H929-W968

Vulnerability from github – Published: 2026-02-10 00:25 – Updated: 2026-02-10 02:56

Summary

File Browser has a Path-Based Access Control Bypass via Multiple Leading Slashes in URL

Details

Summary

An authenticated user can bypass the application's "Disallow" file path rules by modifying the request URL. By adding multiple slashes (e.g., //private/) to the path, the authorization check fails to match the rule, while the underlying filesystem resolves the path correctly, granting unauthorized access to restricted files.

Details

The vulnerability allows users to bypass "Disallow" rules defined by administrators.

The issue stems from how the application handles URL path normalization and rule matching:

Router Configuration: The router in http/http.go is configured with r.SkipClean(true). This prevents the automatic collapse of multiple slashes (e.g., // becoming /) before the request reaches the handler.
Insecure Rule Matching: The rule enforcement logic in rules/rules.go relies on a simple string prefix match: strings.HasPrefix(path, r.Path). If a rule disallows /private, a request for //private fails this check because //private does not strictly start with /private.
Filesystem Resolution: After bypassing the rule check, the non-normalized path is passed to the filesystem. The filesystem treats the multiple slashes as a single separator, successfully resolving //private/secret.txt and serving the file.

PoC

Python minimal PoC

The following steps demonstrate the vulnerability: 1. Setup: - Admin user creates a folder /private and adds a file /private/secret.txt. Screenshot_20260123_151608 Screenshot_20260123_151551 - Admin adds a Disallow rule for user bob on the path /private. Screenshot_20260123_151502

Verification:
User bob requests GET /api/resources/private/secret.txt.
Server responds: 403 Forbidden.
Exploit:
User bob requests GET /api/resources//private/secret.txt.
Server responds: 200 OK (Bypass successful).

Impact

This vulnerability impacts the confidentiality and integrity of data stored in filebrowser. - Confidentiality: Users can read files they are explicitly forbidden from accessing. - Integrity: If the user has general write permissions but is restricted from specific directories via rules, they can bypass these restrictions to rename, delete, or modify files.

Severity ?

8.1 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Show details on source website

JSON

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.57.0"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/filebrowser/filebrowser/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.57.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-25890"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-706",
      "CWE-863"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-10T00:25:17Z",
    "nvd_published_at": "2026-02-09T22:16:03Z",
    "severity": "HIGH"
  },
  "details": "### Summary\nAn authenticated user can bypass the application\u0027s \"Disallow\" file path rules by modifying the request URL. By adding multiple slashes (e.g., //private/) to the path, the authorization check fails to match the rule, while the underlying filesystem resolves the path correctly, granting unauthorized access to restricted files.\n\n### Details\nThe vulnerability allows users to bypass \"Disallow\" rules defined by administrators.\n\nThe issue stems from how the application handles URL path normalization and rule matching:\n\n1. Router Configuration: The router in `http/http.go` is configured with `r.SkipClean(true)`. This prevents the automatic collapse of multiple slashes (e.g., // becoming /) before the request reaches the handler.\n2. Insecure Rule Matching: The rule enforcement logic in `rules/rules.go` relies on a simple string prefix match: `strings.HasPrefix(path, r.Path)`. If a rule disallows /private, a request for //private fails this check because //private does not strictly start with /private.\n3. Filesystem Resolution: After bypassing the rule check, the non-normalized path is passed to the filesystem. The filesystem treats the multiple slashes as a single separator, successfully resolving //private/secret.txt and serving the file.\n\n### PoC\n[Python minimal PoC](https://github.com/user-attachments/files/24823114/poc.py)\n\nThe following steps demonstrate the vulnerability:\n1. Setup:\n  - Admin user creates a folder /private and adds a file /private/secret.txt.\n\u003cimg width=\"971\" height=\"719\" alt=\"Screenshot_20260123_151608\" src=\"https://github.com/user-attachments/assets/2071c92e-2bbe-46f8-a338-05b0f53d381a\" /\u003e\n\u003cimg width=\"890\" height=\"386\" alt=\"Screenshot_20260123_151551\" src=\"https://github.com/user-attachments/assets/1def540a-de26-4666-a6ab-058d5927bfbe\" /\u003e\n  - Admin adds a Disallow rule for user bob on the path /private.\n\u003cimg width=\"1005\" height=\"1126\" alt=\"Screenshot_20260123_151502\" src=\"https://github.com/user-attachments/assets/e9b57d59-f4ab-41d8-b056-8ffdaa219963\" /\u003e\n\n2. Verification:\n  - User bob requests GET /api/resources/private/secret.txt.\n  - Server responds: 403 Forbidden.\n\u003cimg width=\"1193\" height=\"721\" alt=\"Screenshot_20260123_154446\" src=\"https://github.com/user-attachments/assets/dd092a10-2f8c-4a3c-b48f-d540c483bb5a\" /\u003e\n3. Exploit:\n  - User bob requests GET /api/resources//private/secret.txt.\n  - Server responds: 200 OK (Bypass successful).\n\u003cimg width=\"1193\" height=\"721\" alt=\"Screenshot_20260123_154544\" src=\"https://github.com/user-attachments/assets/27ebb82c-f7c2-467d-ae82-f495ae3aa2d4\" /\u003e\n\u003cimg width=\"1196\" height=\"818\" alt=\"Screenshot_20260123_154618\" src=\"https://github.com/user-attachments/assets/82035884-9a24-490d-b928-7bdd2dbe3193\" /\u003e\n\n\n### Impact\nThis vulnerability impacts the confidentiality and integrity of data stored in filebrowser.\n- Confidentiality: Users can read files they are explicitly forbidden from accessing.\n- Integrity: If the user has general write permissions but is restricted from specific directories via rules, they can bypass these restrictions to rename, delete, or modify files.",
  "id": "GHSA-4mh3-h929-w968",
  "modified": "2026-02-10T02:56:37Z",
  "published": "2026-02-10T00:25:17Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/filebrowser/filebrowser/security/advisories/GHSA-4mh3-h929-w968"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-25890"
    },
    {
      "type": "WEB",
      "url": "https://github.com/filebrowser/filebrowser/commit/489af403a19057f6b6b4b1dc0e48cbb26a202ef9"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/filebrowser/filebrowser"
    },
    {
      "type": "WEB",
      "url": "https://github.com/filebrowser/filebrowser/releases/tag/v2.57.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "File Browser has a Path-Based Access Control Bypass via Multiple Leading Slashes in URL"
}

CVE-2026-25890 (GCVE-0-2026-25890)

Vulnerability from cvelistv5 – Published: 2026-02-09 21:21 – Updated: 2026-02-10 15:57

Title

File Browser has a Path-Based Access Control Bypass via Multiple Leading Slashes in URL

Summary

File Browser provides a file managing interface within a specified directory and it can be used to upload, delete, preview, rename and edit files. Prior to 2.57.1, an authenticated user can bypass the application's "Disallow" file path rules by modifying the request URL. By adding multiple slashes (e.g., //private/) to the path, the authorization check fails to match the rule, while the underlying filesystem resolves the path correctly, granting unauthorized access to restricted files. This vulnerability is fixed in 2.57.1.

Severity ?

8.1 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

CWE

CWE-706 - Use of Incorrectly-Resolved Name or Reference
CWE-863 - Incorrect Authorization

Assigner

GitHub_M

References

URL

Tags

	https://github.com/filebrowser/filebrowser/securi…	x_refsource_CONFIRM
	https://github.com/filebrowser/filebrowser/commit…	x_refsource_MISC
	https://github.com/filebrowser/filebrowser/releas…	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	filebrowser	filebrowser	Affected: < 2.57.2

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-25890",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-02-10T15:32:03.411722Z",
                "version": "2.0.3"
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          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
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          "product": "filebrowser",
          "vendor": "filebrowser",
          "versions": [
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            }
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          "lang": "en",
          "value": "File Browser provides a file managing interface within a specified directory and it can be used to upload, delete, preview, rename and edit files. Prior to 2.57.1, an authenticated user can bypass the application\u0027s \"Disallow\" file path rules by modifying the request URL. By adding multiple slashes (e.g., //private/) to the path, the authorization check fails to match the rule, while the underlying filesystem resolves the path correctly, granting unauthorized access to restricted files. This vulnerability is fixed in 2.57.1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          }
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      ],
      "problemTypes": [
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          "descriptions": [
            {
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              "lang": "en",
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        {
          "descriptions": [
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              "description": "CWE-863: Incorrect Authorization",
              "lang": "en",
              "type": "CWE"
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-09T21:21:50.764Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/filebrowser/filebrowser/security/advisories/GHSA-4mh3-h929-w968",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/filebrowser/filebrowser/security/advisories/GHSA-4mh3-h929-w968"
        },
        {
          "name": "https://github.com/filebrowser/filebrowser/commit/489af403a19057f6b6b4b1dc0e48cbb26a202ef9",
          "tags": [
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        },
        {
          "name": "https://github.com/filebrowser/filebrowser/releases/tag/v2.57.1",
          "tags": [
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          "url": "https://github.com/filebrowser/filebrowser/releases/tag/v2.57.1"
        }
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      "source": {
        "advisory": "GHSA-4mh3-h929-w968",
        "discovery": "UNKNOWN"
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      "title": "File Browser has a Path-Based Access Control Bypass via Multiple Leading Slashes in URL"
    }
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  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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    "datePublished": "2026-02-09T21:21:50.764Z",
    "dateReserved": "2026-02-06T21:08:39.130Z",
    "dateUpdated": "2026-02-10T15:57:52.236Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

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.

Action not permitted

GHSA-4MH3-H929-W968

Summary

Details

PoC

Impact

CVE-2026-25890 (GCVE-0-2026-25890)

Tags

Sightings

Nomenclature