CVE-2025-66255: Critical Unsigned Upload in Mozart FM Transmitter

CVE-2025-66255 is a critical (CVSS 9.8) unauthenticated arbitrary file upload in the Mozart FM Transmitter. The upgrade_contents.php page accepts uploads without checking file headers, cryptographic signatures or the .tgz format, so malicious firmware packages are accepted. The record names no fix, so isolate the interface.

What's affected

• Product: Mozart FM Transmitter from DB Electronica Telecomunicazioni S.p.A. (DB Broadcast), web management interface. The record lists models 30, 50, 100, 300, 500, 1000, 2000, 3000, 3500, 6000 and 7000.
• Component: upgrade_contents.php, the firmware upgrade endpoint.
• Fixed: neither the record nor the researcher write-up we read names a fixed firmware version or a vendor advisory. Contact the vendor for patch status before assuming one exists.
• Severity: the record scores it 9.8 (critical) with the vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. The record shows two weakness classes, missing signature validation and unrestricted upload, and a critical score of 9.8.

How to check if you're exposed

This is a broadcast appliance, so there is no package manager to query. Work from the device and the network.

1. Build a list of every Mozart unit you run, with its model and the web interface version string. The researcher write-up refers to the web management interface version WEBMOZZI-00287.
2. Find out whether the management web interface of each unit is reachable from the internet, from a partner network or from a flat internal network. Check firewall rules and any remote access gateway.
3. Look at the web server logs on a device you can inspect, or at the logs of any proxy in front of it, for requests to the PHP file named in this CVE from addresses you do not recognize.

If the interface is reachable by people outside the small group that needs it, treat the device as exposed.

What to do now

1. Take the management interface off the internet and off any shared network. Put it behind a VPN or a jump host, with an allow list of administrator addresses.
2. Ask DB Broadcast for the patch status of this CVE and for a firmware version that fixes it. Record the answer with your asset notes.
3. Do not apply firmware from any source other than the vendor, and ask the vendor how to verify package integrity.
4. Watch the device for unexpected files, new accounts, changed settings or reboots, and keep a known good copy of its configuration to compare against.
5. Add the rest of your internet facing software to an inventory. Safeguard cannot patch a transmitter, but a free in-browser scan at gold.safeguard.sh/scan and a proper asset inventory help you find the other internet facing software you run, and reachability analysis helps you rank what to fix first.

Why it matters

The record lists CWE-345, CWE-434: CWE-345 is insufficient verification of data authenticity, and CWE-434 is unrestricted upload of dangerous file types. The record says the firmware upgrade endpoint takes any file and does not verify headers, signatures or the expected archive format.

Signed firmware is the control that stops a device from running an attacker's code even if the upload path is exposed. Without a signature check, the upload page is a way to replace the device's software. This is a supply chain style weakness at the device level, because trust in an update should come from a signature and not from who reached the page. The record does not mark this as exploited in the wild and it is not on the CISA KEV list. The advisory trail is thin, since the main public source is a researcher write-up rather than a vendor bulletin, so confirm facts with the vendor. Appliances of this kind sit for years without updates, which is why network isolation is the control you can apply today.

Quick check

Sources

• Researcher write-up: 14 vulnerabilities in the Mozart FM Transmitter web interface
• Safeguard Gold entry

Last reviewed: 18 October 2026.