CVE-2026-48983: 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-...

Description

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.

Metrics

CVSS 3.1

5.8/10

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L

EPSS Probability

0.08%

0.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-367

References

Timeline

Published: Jun 18, 2026
Last Modified: Jun 22, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-48983?

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.

How severe is CVE-2026-48983?

CVE-2026-48983 has a CVSS score of 5.8/10 (MEDIUM severity). The EPSS model estimates a 0.08% probability of exploitation in the next 30 days.

How do I fix CVE-2026-48983?

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.