mcdope pam_usb up to 0.9.2 Environment Variable src/local.c pusb_local_login XRDP_SESSION privileges management

Summaryinfo

A vulnerability was found in mcdope pam_usb up to 0.9.2. It has been declared as critical. This affects the function pusb_local_login of the file src/local.c of the component Environment Variable Handler. Such manipulation of the argument XRDP_SESSION leads to privileges management. This vulnerability is uniquely identified as CVE-2026-64666. The attack can be launched remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in mcdope pam_usb up to 0.9.2. Affected by this issue is the function pusb_local_login of the file src/local.c of the component Environment Variable Handler. The manipulation of the argument XRDP_SESSION with an unknown input leads to a privileges management vulnerability. Using CWE to declare the problem leads to CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-64666 since 07/20/2026. The exploitation is known to be easy. The attack may be launched remotely. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1068 by the MITRE ATT&CK project.

Upgrading to version 0.9.3 eliminates this vulnerability.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• mcdope

Name

• pam_usb

Version

• 0.9.0
• 0.9.1
• 0.9.2

Website

• Product: https://github.com/mcdope/pam_usb/

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CPE 2.2info

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