CVE-2026-85068: NUT blazer_usb ippon_command stack info-leak via unzeroed char tmp[64] in OUT-direction usb_control_msg
Network UPS Tools is a collection of programs which provide a common interface for monitoring and administering UPS, PDU and SCD hardware. From 2.4.2 through 2.8.5, ipponcommand in drivers/blazerusb.c partially initializes char tmp[64] with a short Megatec status query and then passes a fixed eight-byte chunk to usbcontrolmsg. A malicious firmware-controlled USB device presenting the Mustek Powermust VID 0x06da and Mustek Powermust PID 0x0003 matches blazerusbid, selects ipponsubdriver, and can receive the uninitialized trailing stack bytes during normal polling. The disclosure is bounded and read-only, requires physical or supply-chain access to the USB bus, and has no established integrity or availability impact. This issue is scheduled to be fixed in version 2.8.6.
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Network UPS Tools (NUT)to a version that resolves this vulnerability.Fixed in 2.8.6
Event History
Frequently Asked Questions
Which deployments are realistically exposed?
Deployments using NUT versions 2.4.2 through 2.8.5 with a USB device that matches the Mustek Powermust VID 0x06da and PID 0x0003 are exposed when the device is handled by the blazer_usb driver and selects the ippon_subdriver.
What does an attacker need to exploit this issue?
An attacker needs physical or supply-chain access to the USB bus and control of firmware on a malicious USB device presenting the affected Mustek Powermust vendor and product identifiers. The leak occurs during normal polling.
What information can be disclosed?
The device can receive uninitialized trailing stack bytes from a fixed eight-byte USB control transfer after the short Megatec status query is placed in tmp[64]. The disclosure is bounded and read-only; no integrity or availability impact is established.
What should be done if an immediate upgrade is not possible?
Restrict physical and supply-chain access to the USB bus and avoid connecting untrusted USB devices that can present the affected Mustek Powermust identifiers. The scheduled fixed version is 2.8.6.