CVE-2026-48064: high-severity vulnerability in mcdope pam_usb
pam_usb: PAM_RHOST check skipped when deny_remote=false allows XDMCP authentication bypass
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.1epss 0.3%
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/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected products
mcdope · pam_usbRelated CVEs — mcdope pam_usb
In the same product, most dangerous first.
CVE-2026-64669HIGHpam_usb: deny_remote bypassed by compressed IPv6 addresses in pusb_tmux_has_remote_clientsEPSS 0.4%CVE-2026-64668HIGHpam_usb: deny_remote bypassed by zone-indexed IPv6 addresses (fe80::1%eth0) in pusb_tmux_has_remote_clientsEPSS 0.4%CVE-2026-47269HIGHpam_usb: deny_remote feature incorrectly classifies IPv4-mapped IPv6 remote connections as localEPSS 0.3%CVE-2026-47273MEDIUMpam_usb: XPath injection via PAM-supplied identifiers in pam_usb configuration queriesEPSS 0.3%CVE-2026-44711HIGHpam_usb: Symlink attacks on pad directory and pad files enable authentication bypass and root file corruptionEPSS 0.2%CVE-2026-64666HIGHpam_usb: getenv() in pusb_local_login bypasses XRDP deny via env-var unsetEPSS 0.2%