Every CVE Search/ Get API key

CVE-2026-48983

pam_usb: TOCTOU race condition in pad directory creation allows symlink substitution

5.8 Medium

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

0.11%Up 0.1 points since Jun 12, 2026
90%50%10%1%

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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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

History
RecordedChangedSources
first indexedCVE 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.

References

MoveEnter Open