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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-48982
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-18 20:16:14 UTC
Updated2026-06-22 18:16:40 UTC
Descriptionpam_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.

Risk And Classification

Primary CVSS: v3.1 5.8 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L

EPSS: 0.000880000 probability, percentile 0.005100000 (date 2026-06-25)

Problem Types: CWE-362 | CWE-362 CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.8MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L
3.1CNADECLARED5.8MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
High
Availability
Low

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mcdope Pam Usb affected < 0.9.2 Not specified

References

ReferenceSourceLinkTags
github.com/mcdope/pam_usb/security/advisories/GHSA-hxh6-9574-5vp6 [email protected] github.com
github.com/mcdope/pam_usb/releases/tag/0.9.2 [email protected] github.com
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