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CVE-2026-48982

pam_usb: Missing O_EXCL on pad temp file creation allows concurrent update race PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
mcdope / pam_usbaffected < 0.9.2

CWE

CWE-362

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.