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.
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History
Wed, 27 May 2026 20:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | pam_usb: OTP pad authentication bypass via missing system pad check and uninitialized RNG buffer | |
| Weaknesses | CWE-287 CWE-908 |
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cvssV3_1
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-05-27T20:06:15.388Z
Reserved: 2026-05-18T23:03:37.230Z
Link: CVE-2026-47272
No data.
Status : Received
Published: 2026-05-27T20:16:39.747
Modified: 2026-05-27T20:16:39.747
Link: CVE-2026-47272
No data.
OpenCVE Enrichment
No data.