CVE-2026-48982
MediumCVSS 5.8Exploitation Probability (EPSS)
Low risk1th percentile — higher than 1% of all known CVEs
Summary
In versions prior to 0.9.2, pam_usb creates a temporary file without the O_EXCL flag when updating a one-time pad file. This can lead to a situation where two concurrent processes updating the same pad may both succeed, resulting in overwriting the pad value.
Risk Assessment
This may lead to a divergence in the pad value, potentially causing authentication failures or creating a window for pad reuse in a precisely timed attack.
Recommendation
It is recommended to upgrade to version 0.9.2 or later to mitigate this vulnerability.
Original NVD description (English source)
pam_usb provides hardware authentication for Linux using ordinary removable media. In versions prior to 0.9.2, when updating a one-time pad file, a temporary file is created using open() without the O_EXCL flag. Without O_EXCL, the create operation is not atomic: two concurrent processes racing to update the same pad may both succeed in opening the file, with the second write silently overwriting the first. The one-time pad is the core replay-prevention mechanism of pam_usb. A successful race could result in the stored pad value diverging from what either process expected, potentially causing authentication failures or, in a precisely timed attack, creating a window for pad reuse. This issue has been fixed in version 0.9.2.