CVE-2026-47272
HighSummary
In versions prior to 0.9.0, the pusb_pad_compare() function in pam_usb did not enforce the presence and readability of the pad file on the USB device, allowing users to authenticate without the physical device. A user could delete their ~/.pamusb/device.pad, resulting in successful authentication without the required USB device.
Risk Assessment
This vulnerability poses a risk of unauthorized access to the system, as a local user can bypass the requirement of having a physical USB device for authentication.
Recommendation
It is recommended to upgrade to version 0.9.0 or later to eliminate this vulnerability and to implement additional security measures to monitor and protect system access.
Original NVD description (English source)
pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.0, the pusb_pad_compare() function in src/pad.c only verified that the user-side pad (~/.pamusb/device.pad) could be read, but did not enforce that the system-side pad (the pad file on the USB device) was also present and readable. If the user-side pad was deleted or unreadable, the function returned a failure that was treated as non-fatal in certain code paths, allowing authentication to succeed without the USB device being verified. A local user can delete their own ~/.pamusb/device.pad to remove the USB device requirement and authenticate without the physical device. This vulnerability is fixed in 0.9.0.