CVE-2026-64668pam_usb: deny_remote bypassed by zone-indexed IPv6 addresses (fe80::1%eth0) in pusb_tmux_has_remote_clients
- 7.4HighCVSS base score
- 0.38%Exploitation in 30 daysEPSS · top 67% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By GitHub_M
- 4 months later
· 4 months later
Published
- 1 day later
· 1 day later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High7.4 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |
| NVDNVD · Received | 3.1 | High7.4 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.38% · top 67% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.4.
Affected products
References
References4
- https://github.com/mcdope/pam_usb/security/advisories/GHSA-7583-9cqv-j9rf (opens in a new tab)x_refsource_CONFIRM
- https://github.com/mcdope/pam_usb/pull/423 (opens in a new tab)x_refsource_MISC
- https://github.com/mcdope/pam_usb/commit/a62513f3da871d6576d751de3482eb80b9ac79f3 (opens in a new tab)x_refsource_MISC
- https://github.com/mcdope/pam_usb/releases/tag/0.9.3 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-123130 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-64668)Record last updated .