CVE-2026-47272CWE-287CWE-908

pam_usb: OTP pad authentication bypass via missing system pad check and uninitialized RNG buffer

High · published May 27, 2026

CVSS v3.1
7.1
EPSS
0%
Percentile
5.4
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.1 · HIGH
Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00165 · 5.4th percentile
Weaknesses
CWE-287 · Improper Authentication; CWE-908 · Use of Uninitialized Resource
Published
2026-05-27T20:06Z
EPSS history
Timeline
  • 27 MAY 20:06Z
    pam_usb: OTP pad authentication bypass via missing system pad check and uninitialized RNG buffer
    cvelistv5