CVE-2026-64668
pam_usb: deny_remote bypassed by zone-indexed IPv6 addresses (fe80::1%eth0) in pusb_tmux_has_remote_clients
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 pattern matched the address group and then immediately expected whitespace. On Linux systems with multi-homed network interfaces, w -i appends a zone index (scope identifier) to link-local IPv6 addresses — e.g. fe80::1%eth0. The %eth0 suffix appeared between the address and the next whitespace field, causing the regex match to fail even for an otherwise-matching remote session. The function returned "no remote clients" and granted access. This issue has been patched in version 0.9.3.
INFO
Published Date :
Nov. 11, 2026, 3:50 a.m.
Last Modified :
Nov. 11, 2026, 3:50 a.m.
Remotely Exploit :
Yes !
Source :
GitHub_M
Affected Products
The following products are affected by CVE-2026-64668
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | MITRE-CVE |
Solution
- Update pam_usb to version 0.9.3 or later.
- Apply vendor-supplied patches for pam_usb.
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