Description
pam_usb provides hardware authentication for Linux using removable media. From version 0.8.0 to before version 0.9.3, the deny_remote feature in pam_usb uses /usr/bin/w -i to detect whether the authenticating user has an active remote tmux session. In pusb_tmux_has_remote_clients() (src/tmux.c), the IPv6 detection regex required exactly four explicit colon-separated groups of 1-4 hex digits (e.g. 2001:0db8:85a3:0000). Any IPv6 address in compressed notation — including loopback (::1), link-local (fe80::1), and global unicast addresses (2001:db8::1) — did not match this pattern. As a result the remote-client check silently returned "no remote clients" even when a remote tmux client was connected from such an address. This issue has been patched in version 0.9.3.
Published: 2026-11-11
Score: 7.4 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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History

Wed, 11 Nov 2026 04:00:00 +0000

Type Values Removed Values Added
Description pam_usb provides hardware authentication for Linux using removable media. From version 0.8.0 to before version 0.9.3, the deny_remote feature in pam_usb uses /usr/bin/w -i to detect whether the authenticating user has an active remote tmux session. In pusb_tmux_has_remote_clients() (src/tmux.c), the IPv6 detection regex required exactly four explicit colon-separated groups of 1-4 hex digits (e.g. 2001:0db8:85a3:0000). Any IPv6 address in compressed notation — including loopback (::1), link-local (fe80::1), and global unicast addresses (2001:db8::1) — did not match this pattern. As a result the remote-client check silently returned "no remote clients" even when a remote tmux client was connected from such an address. This issue has been patched in version 0.9.3.
Title pam_usb: deny_remote bypassed by compressed IPv6 addresses in pusb_tmux_has_remote_clients
Weaknesses CWE-285
CWE-693
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-11-11T03:52:43.930Z

Reserved: 2026-07-20T17:12:12.891Z

Link: CVE-2026-64669

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses