CVE-2025-66263 in Mozart FM Transmitter
Summary
by MITRE • 11/26/2025
Unauthenticated Arbitrary File Read via Null Byte Injection in DB Electronica Telecomunicazioni S.p.A. Mozart FM Transmitter versions 30, 50, 100, 300, 500, 1000, 2000, 3000, 3500, 6000, 7000 allows an attacker to perform Null byte injection in download_setting.php allows reading arbitrary files. The `/var/tdf/download_setting.php` endpoint constructs file paths by concatenating user-controlled `$_GET['filename']` with a forced `.tgz` extension. Running on PHP 5.3.2 (pre-5.3.4), the application is vulnerable to null byte injection (%00), allowing attackers to bypass the extension restriction and traverse paths. By requesting `filename=../../../../etc/passwd%00`, the underlying C functions treat the null byte as a string terminator, ignoring the appended `.tgz` and enabling unauthenticated arbitrary file disclosure of any file readable by the web server user.
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Analysis
by VulDB Data Team • 12/04/2025
The vulnerability identified as CVE-2025-66263 affects DB Electronica Telecomunicazioni S.p.A. Mozart FM Transmitter versions 30, 50, 100, 300, 500, 1000, 2000, 3000, 3500, 6000, and 7000 which operate on PHP 5.3.2. This critical security flaw exists within the `/var/tdf/download_setting.php` endpoint where the application constructs file paths by directly concatenating user-supplied input from the `$_GET['filename']` parameter with a hardcoded `.tgz` extension. The vulnerability stems from the application's failure to properly sanitize user input before path construction, creating an opportunity for null byte injection attacks that exploit a known weakness in PHP versions prior to 5.3.4. The specific technical flaw manifests when an attacker crafts a malicious request containing a null byte character (%00) followed by a target file path, allowing the application to bypass the intended file extension restriction and access arbitrary files on the system.
The operational impact of this vulnerability is severe and far-reaching for organizations using affected Mozart FM Transmitter devices. An unauthenticated attacker can leverage this null byte injection flaw to read any file that is accessible to the web server user account, potentially exposing sensitive system information including but not limited to password files, configuration settings, database credentials, and application source code. The vulnerability enables path traversal attacks that can escalate beyond simple file disclosure to full system compromise, as attackers can access critical system files such as `/etc/passwd`, `/etc/shadow`, or application configuration files that may contain database connection strings and other sensitive information. This weakness particularly affects industrial control systems and telecommunications equipment where the devices are often deployed in environments with limited network segmentation and where the web interface provides direct access to system resources without adequate authentication controls.
The vulnerability aligns with CWE-77 and CWE-22 categories under the Common Weakness Enumeration framework, specifically representing a path traversal vulnerability that allows attackers to access files outside the intended directory structure. From an adversarial perspective, this vulnerability maps to several ATT&CK techniques including T1083 (File and Directory Discovery) and T1566 (Phishing with Malicious Attachments) as attackers can discover and exfiltrate sensitive files from the compromised system. The null byte injection technique utilized in this attack is a well-documented method that exploits PHP's handling of null characters in string operations, where the null byte acts as a string terminator in underlying C functions, effectively truncating the filename and allowing access to unintended files. This vulnerability demonstrates the importance of proper input validation and the dangers of using outdated software versions that contain known security weaknesses.
Organizations should implement immediate mitigations including upgrading to patched versions of the Mozart FM Transmitter software, applying the latest security updates from DB Electronica Telecomunicazioni S.p.A., and implementing network segmentation to limit access to the affected devices. Access controls should be strengthened by requiring authentication for all administrative functions and by implementing proper input validation at multiple layers of the application stack. Additionally, organizations should consider deploying web application firewalls to detect and block malicious requests containing null byte sequences, and implement regular security assessments of industrial control systems to identify similar vulnerabilities in other networked devices. The use of modern PHP versions that properly handle null bytes in string operations should be mandated across all systems to prevent similar vulnerabilities from being introduced through legacy code implementations.