CVE-2026-64666
pam_usb: getenv() in pusb_local_login bypasses XRDP deny via env-var unset
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.
INFO
Published Date :
Nov. 11, 2026, 3:51 a.m.
Last Modified :
Nov. 11, 2026, 3:51 a.m.
Remotely Exploit :
No
Source :
GitHub_M
Affected Products
The following products are affected by CVE-2026-64666
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.
- Apply vendor patches if available.
- Review environment variable handling.
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CVE-2026-64666 vulnerability anywhere in the article.