CVE-2026-48064

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.

CVSS 3.1

8.1CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

0.3% chance of exploitation in the next 30 days; higher than 27% of CVEs (scores of 2026-10-25)

CWE

CWE-863

Published

2026-05-27

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

References

• https://github.com/mcdope/pam_usb/issues/348
• https://github.com/mcdope/pam_usb/security/advisories/GHSA-w38v-cw9r-x9p6
• https://github.com/mcdope/pam_usb/issues/348

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