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.

No CVSS v4.0

Attack Vector Local

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact Low

Integrity Impact High

Availability Impact Low

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
mcdope pam_usb affected
Version Status Constraints
< 0.9.2 affected —

No data.

No data.

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Vendors Products
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Pam Usb Subscribe

Project Subscriptions

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Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/mcdope/pam_usb/releases/tag/0.9.2 cve-icon
https://github.com/mcdope/pam_usb/security/advisories/GHSA-hxh6-9574-5vp6 cve-icon
History

Thu, 18 Jun 2026 21:30:00 +0000

Type Values Removed Values Added
First Time appeared Mcdope
Mcdope pam Usb
Vendors & Products Mcdope
Mcdope pam Usb

Thu, 18 Jun 2026 19:45:00 +0000

Type Values Removed Values Added
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.
Title pam_usb: Missing O_EXCL on pad temp file creation allows concurrent update race
Weaknesses CWE-362
References
Metrics cvssV3_1

{'score': 5.8, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-06-18T19:01:08.766Z

Reserved: 2026-05-26T23:26:07.974Z

Link: CVE-2026-48982

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-18T21:30:16Z

Weaknesses