CVE-2026-48064 Details
Description
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.
A vulnerability in pam_usb prior to version 0.9.1 allows remote authentication bypass through XDMCP connections. When the PAM service is set to deny_remote=false, the PAM_RHOST check is skipped, enabling authentication without proper locality verification. This issue affects display managers like GDM, SDDM, and LightDM, as well as the xscreensaver locker in VNC sessions.
Users should update to pam_usb version 0.9.1 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed May 27, 2026CISA-ADP
Assessed Jun 2, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/mcdope/pam_usb/issues/348 | CISA-ADP | Issue TrackingTechnical DescriptionVendor |
| https://github.com/mcdope/pam_usb/issues/348 | [email protected] | Issue TrackingTechnical DescriptionVendor |
| https://github.com/mcdope/pam_usb/security/advisories/GHSA-w38v-cw9r-x9p6 | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-863 | Incorrect Authorization | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| pam_usb | <= 0.9.0 (semver) |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Jun 2, 2026 | CVE Modified | CISA-ADP |
| May 27, 2026 | New CVE Received | [email protected] |