CVE-2026-48982
pam_usb: Missing O_EXCL on pad temp file creation allows concurrent update race
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.
| CWE | CWE-362 |
| Vendor | mcdope |
| Product | pam_usb |
| Published | Jun 18, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L