CVE-2026-48982: CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') in mcdope pam_usb
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.
AI Analysis
Technical Summary
CVE-2026-48982 describes a race condition vulnerability (CWE-362) in mcdope's pam_usb prior to version 0.9.2. When updating the one-time pad file used for hardware authentication, the temporary file creation lacks the O_EXCL flag, making the operation non-atomic. Concurrent processes can both open and write to the file, causing the stored pad to diverge from expected values. This undermines the replay-prevention mechanism and may cause authentication failures or enable a window for pad reuse. The vulnerability is resolved in pam_usb version 0.9.2.
Potential Impact
The vulnerability can cause the one-time pad used for replay prevention to become inconsistent due to concurrent writes. This may lead to authentication failures or, in a precisely timed attack, allow reuse of the pad, weakening the security of the hardware authentication mechanism. The CVSS score of 5.8 reflects a medium severity with limited attack vector (local), high complexity, and partial impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Upgrade pam_usb to version 0.9.2 or later, where the race condition has been fixed by ensuring atomic file creation with the O_EXCL flag. No other mitigations are indicated.
CVE-2026-48982: CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') in mcdope pam_usb
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.
CVSS v3.1
Score 5.8medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-48982 describes a race condition vulnerability (CWE-362) in mcdope's pam_usb prior to version 0.9.2. When updating the one-time pad file used for hardware authentication, the temporary file creation lacks the O_EXCL flag, making the operation non-atomic. Concurrent processes can both open and write to the file, causing the stored pad to diverge from expected values. This undermines the replay-prevention mechanism and may cause authentication failures or enable a window for pad reuse. The vulnerability is resolved in pam_usb version 0.9.2.
Potential Impact
The vulnerability can cause the one-time pad used for replay prevention to become inconsistent due to concurrent writes. This may lead to authentication failures or, in a precisely timed attack, allow reuse of the pad, weakening the security of the hardware authentication mechanism. The CVSS score of 5.8 reflects a medium severity with limited attack vector (local), high complexity, and partial impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Upgrade pam_usb to version 0.9.2 or later, where the race condition has been fixed by ensuring atomic file creation with the O_EXCL flag. No other mitigations are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-26T23:26:07.974Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a344c3bf198dc38c1709d81
Added to database: 06/18/2026, 19:51:23 UTC
Last enriched: 06/25/2026, 21:15:43 UTC
Last updated: 08/01/2026, 19:18:00 UTC
Views: 75
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