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CVE-2026-48982 - pam_usb: Missing O_EXCL on pad temp file creation allows concurrent update race

CVE ID :CVE-2026-48982
Published : June 18, 2026, 7:01 p.m. | 2 hours, 38 minutes ago
Description :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.
Severity: 0.0 | NA
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