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CVE-2026-48982 mcdope CVE debrief

CVE-2026-48982 is a MEDIUM-severity vulnerability affecting pam_usb, a Linux authentication module that uses removable media for hardware authentication. In pam_usb versions prior to 0.9.2, a race condition occurs when updating a one-time pad file. This condition arises because the update process creates a temporary file using open() without the O_EXCL flag, making the create operation non-atomic. Two concurrent processes can open and write to the file, causing the stored pad value to diverge and potentially leading to authentication failures or pad reuse. This issue has been fixed in version 0.9.2. Users should update to the latest version to mitigate this vulnerability.

Vendor
mcdope
Product
pam_usb
CVSS
MEDIUM 5.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-18
Original CVE updated
2026-06-22
Advisory published
2026-06-18
Advisory updated
2026-06-22

Who should care

System administrators and security professionals responsible for Linux systems using pam_usb for authentication should be aware of this vulnerability. They should assess their systems for potential exposure and update pam_usb to version 0.9.2 or later to prevent exploitation.

Technical summary

The vulnerability exists in the pam_usb module, specifically in the one-time pad file update process. When updating the pad file, pam_usb creates a temporary file without using the O_EXCL flag with open(). This allows multiple processes to open and write to the file simultaneously, potentially causing the pad values to become inconsistent. The CVSS score for this vulnerability is 5.8, indicating a MEDIUM severity level. The vulnerability is categorized under CWE-362, which involves race conditions.

Defensive priority

MEDIUM

Recommended defensive actions

  • Update pam_usb to version 0.9.2 or later to fix the race condition vulnerability.
  • Review system configurations to ensure only authorized processes can access and modify authentication files.
  • Implement additional monitoring to detect potential authentication anomalies that could indicate exploitation attempts.
  • Consider using alternative authentication methods if updating pam_usb is not feasible.
  • Regularly review and update Linux systems and authentication modules to ensure they are secure and up-to-date.
  • Limit access to sensitive authentication files and directories.
  • Use secure coding practices when developing or modifying authentication modules.

Evidence notes

The information provided is based on the CVE-2026-48982 record from the National Vulnerability Database (NVD) and details from the pam_usb GitHub repository. The vulnerability was published and modified on June 18, 2026. The CVSS score is 5.8, indicating a MEDIUM severity level. The CWE classification for this vulnerability is CWE-362, which involves race conditions.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-48982 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-48982

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-48982 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-48982

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.