CVE-2026-47272: CWE-287: Improper Authentication in mcdope pam_usb
CVE-2026-47272 is a high-severity vulnerability in pam_usb versions prior to 0.9.0 that allows improper authentication. The flaw exists because the authentication function pusb_pad_compare() only verified the presence and readability of the user-side pad file (~/. pamusb/device.pad) but did not enforce verification of the system-side pad file on the USB device. If the user-side pad file is deleted or unreadable, the function returns a failure treated as non-fatal in some code paths, enabling a local user to bypass the USB device requirement and authenticate without the physical device. This vulnerability is fixed in version 0.9.0.
AI Analysis
Technical Summary
The vulnerability in pam_usb before version 0.9.0 arises from the pusb_pad_compare() function in src/pad.c, which fails to require the system-side pad file on the USB device to be present and readable during authentication. Instead, it only checks the user-side pad file. If the user-side pad file is missing or unreadable, the function returns a failure that certain code paths treat as non-fatal, allowing authentication to succeed without verifying the USB device. This improper authentication flaw (CWE-287) enables a local user to bypass the USB hardware authentication mechanism by deleting their ~/.pamusb/device.pad file. The issue is resolved in pam_usb version 0.9.0.
Potential Impact
A local attacker can bypass the USB device authentication requirement by deleting their user-side pad file, allowing unauthorized access without the physical USB device. This compromises the integrity and confidentiality of the authentication process, potentially granting elevated privileges or unauthorized system access. The vulnerability does not affect availability and requires local access with low privileges to exploit.
Mitigation Recommendations
Upgrade pam_usb to version 0.9.0 or later, where this vulnerability is fixed. There is no indication of an official patch advisory beyond this version update. Until upgraded, users should be aware that deleting the ~/.pamusb/device.pad file can bypass authentication, so restricting local user permissions and monitoring for such file deletions may help mitigate risk.
CVE-2026-47272: CWE-287: Improper Authentication in mcdope pam_usb
Description
CVE-2026-47272 is a high-severity vulnerability in pam_usb versions prior to 0.9.0 that allows improper authentication. The flaw exists because the authentication function pusb_pad_compare() only verified the presence and readability of the user-side pad file (~/. pamusb/device.pad) but did not enforce verification of the system-side pad file on the USB device. If the user-side pad file is deleted or unreadable, the function returns a failure treated as non-fatal in some code paths, enabling a local user to bypass the USB device requirement and authenticate without the physical device. This vulnerability is fixed in version 0.9.0.
CVSS v3.1
Score 7.1high
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in pam_usb before version 0.9.0 arises from the pusb_pad_compare() function in src/pad.c, which fails to require the system-side pad file on the USB device to be present and readable during authentication. Instead, it only checks the user-side pad file. If the user-side pad file is missing or unreadable, the function returns a failure that certain code paths treat as non-fatal, allowing authentication to succeed without verifying the USB device. This improper authentication flaw (CWE-287) enables a local user to bypass the USB hardware authentication mechanism by deleting their ~/.pamusb/device.pad file. The issue is resolved in pam_usb version 0.9.0.
Potential Impact
A local attacker can bypass the USB device authentication requirement by deleting their user-side pad file, allowing unauthorized access without the physical USB device. This compromises the integrity and confidentiality of the authentication process, potentially granting elevated privileges or unauthorized system access. The vulnerability does not affect availability and requires local access with low privileges to exploit.
Mitigation Recommendations
Upgrade pam_usb to version 0.9.0 or later, where this vulnerability is fixed. There is no indication of an official patch advisory beyond this version update. Until upgraded, users should be aware that deleting the ~/.pamusb/device.pad file can bypass authentication, so restricting local user permissions and monitoring for such file deletions may help mitigate risk.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-18T23:03:37.230Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a17519de29bf47b50e771a5
Added to database: 05/27/2026, 20:18:37 UTC
Last enriched: 06/03/2026, 20:53:21 UTC
Last updated: 07/31/2026, 19:22:59 UTC
Views: 56
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