pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.1, when a PAM service is configured with deny_remote=false in pam_usb (commonly done for display managers such as gdm-password or lightdm to bypass process/TTY heuristics for local sessions), the PAM_RHOST check in pusb_do_auth() is also skipped. PAM_RHOST is set by remote daemons (sshd, XDMCP servers) to identify the remote client address. Because the check is gated inside if (opts.deny_remote), a genuine remote XDMCP connection reaches the USB device authentication step instead of being rejected. This vulnerability is fixed in 0.9.1.
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 0.9.1, when a PAM service is configured with deny_remote=false in pam_usb (commonly done for display managers such as gdm-password or lightdm to bypass process/TTY heuristics for local sessions), the PAM_RHOST check in pusb_do_auth() is also skipped. PAM_RHOST is set by remote daemons (sshd, XDMCP servers) to identify the remote client address. Because the check is gated inside if (opts.deny_remote), a genuine remote XDMCP connection reaches the USB device authentication step instead of being rejected. This vulnerability is fixed in 0.9.1.
Title pam_usb: PAM_RHOST check skipped when deny_remote=false allows XDMCP authentication bypass
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-27T19:59:53.496Z

Reserved: 2026-05-20T18:25:25.707Z

Link: CVE-2026-48064

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-05-27T20:16:40.230

Modified: 2026-05-27T20:16:40.230

Link: CVE-2026-48064

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.