CVE-2026-48983
pam_usb: TOCTOU race condition in pad directory creation allows symlink substitution
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.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- High
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- Low
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
5.8
pam_usb: TOCTOU race condition in pad directory creation allows symlink substitution
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.
- Record
CVE-2026-48983- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L - Weakness
- CWE-367
- Updated
- 2026-11-02
EUVDEUVD-2026-37936
5.8
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.
- Record
EUVD-2026-37936- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L - Updated
- 2026-11-02
NVD
5.8
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.
- Record
CVE-2026-48983- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L - Weakness
- CWE-367
- Updated
- 2026-11-02
OSV
5.8
pam_usb: TOCTOU race condition in pad directory creation allows symlink substitution
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.
- Record
CVE-2026-48983- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L - Weakness
- CWE-367
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-48983 is a medium vulnerability (CVSS 5.8) in Mcdope Pam Usb, published June 18, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.11%, the 1st percentile. No source names a fixed version.