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Race ConditionWeakness · CWE-362

CVE-2026-48982

MEDIUM · 5.8 CVSS v3.1 Published 2026-06-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
60/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In pam_usb versions prior to 0.9.2, the one-time pad file update uses open() without O_EXCL, creating a race condition where concurrent processes can both open the same file and the second write silently overwrites the first. This compromises the core replay-prevention mechanism, potentially causing authentication failures or pad reuse.

MitigationUpgrade pam_usb to version 0.9.2 or later, which includes the fix using O_EXCL flag for atomic file creation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
High
Privileges
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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify pam_usb is installed
    Check for pam_usb package via package manager (e.g., dpkg -l | grep pam-usb, rpm -qa | grep pam-usb, or which pluggable-authentication-modules) or look for /lib/security/pam_usb.so or /lib64/security/pam_usb.so
    Affected if pam_usb is not installed on the system
  2. Determine pam_usb version
    Run pam_usb version command if available, or query package manager (e.g., dpkg -s pam-usb, rpm -qi pam-usb), or check any version file in the pam_usb installation directory
    Affected if version is present and less than 0.9.2
  3. Identify one-time pad configuration
    Look for .usbpad, otp, or pad file references in pam_usb configuration directories such as /etc/pam_usb/, ~/.pam_usb/, or check user home directories for hidden .usb configuration files containing pad file paths
    Affected if one-time pad files are configured or present in pam_usb configuration
  4. Locate active pad files
    Inspect the identified pad file paths from configuration to confirm the files exist on disk; these files contain the one-time pad data used for authentication replay prevention
    Affected if pad files exist and the version is vulnerable (< 0.9.2)
  5. Check for concurrent pad update processes
    Monitor or review system logs for authentication events, or inspect running processes to see if multiple pam_usb authentication attempts could occur simultaneously updating the same pad file
    Affected if concurrent authentication attempts target the same pad file and version is vulnerable

User is affected if pam_usb version is below 0.9.2 AND the one-time pad (OTP) replay-prevention mechanism is configured and actively used on the system.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade pam_usb to version 0.9.2 or later, which includes the fix using O_EXCL flag for atomic file creation.

Recommended fix High confidence

0.9.2

  1. Upgrade pam_usb to version 0.9.2 or later. Use your distribution's package manager to update (e.g., apt update && apt upgrade pam-usb, yum update pam-usb, or dnf update pam-usb depending on your Linux distribution).
  2. If installing from source, download version 0.9.2 from the official repository and rebuild/install using standard build procedures (./configure, make, make install).
  3. After upgrading, verify the installed version matches 0.9.2 or later to confirm the fix is applied.

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,190
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-48982 in production — separate from our analysis above.

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