CVE-2026-64666highCWE-807

CVE-2026-64666: high-severity vulnerability in mcdope pam_usb

pam_usb: getenv() in pusb_local_login bypasses XRDP deny via env-var unset

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21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 7.1epss 0.2%
pam_usb provides hardware authentication for Linux using removable media. Prior to version 0.9.3, src/local.c reads XRDP_SESSION with plain getenv(3) at the head of pusb_local_login while every other env consumer in the same function uses secure_getenv(3). When pam_usb.so loads into a setuid PAM host, the calling user controls the environment passed in. Clearing XRDP_SESSION before invoking the host bypasses the explicit XRDP-deny rule. Other remote-detection signals (rmsvc, evdev, loginctl, utmp) may still catch the session, but the env-based detection alone is defeated. This issue has been patched in version 0.9.3.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Affected products
mcdope · pam_usb
Related 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-2026-48064HIGHpam_usb: PAM_RHOST check skipped when deny_remote=false allows XDMCP authentication bypassEPSS 0.3%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%