PatchSiren cyber security CVE debrief
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.
Official resources
CVE-2026-48982 was published and modified on 2026-06-18T20:16:14.530Z.