CVE-2026-48983
MediumCVSS 5.8Summary
In versions prior to 0.9.2, pam_usb has a symlink race condition in per-device and per-user pad directory creation. A local attacker can exploit this vulnerability by replacing the target path with a symlink to a directory they control.
Risk Assessment
This vulnerability may allow pad files to be written to an attacker-controlled location, potentially exposing future pad values or disrupting the authentication process.
Recommendation
It is recommended to upgrade to version 0.9.2 or later to mitigate this security issue.
Original NVD description (English source)
pam_usb provides hardware authentication for Linux using ordinary removable media. In versions prior to 0.9.2, a symlink race condition exists in per-device and per-user pad directory creation. pam_usb uses a check-then-act pattern: it calls lstat() to test for existence and then calls mkdir() separately to create the directory. A local attacker can win the race between these calls by replacing the target path with a symlink to a directory they control. If successful, one-time pad files may be written to an attacker-controlled location, potentially exposing future pad values before use or disrupting authentication. This issue has been fixed in version 0.9.2.