CVE-2026-64666

HIGHCVSS 7.1/10

Last modified

CVE-2026-64666 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. 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).

Description

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.

Metrics

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
mcdopepam_usb< 0.9.3

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-64666?
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.
How severe is CVE-2026-64666?
CVE-2026-64666 has a CVSS score of 7.1/10 (HIGH severity).
How do I fix CVE-2026-64666?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST