CVE-2026-48986 PUBLISHED

pam_usb: Infinite loop DoS in process-tree walk when parent process exits during authentication

Assigner: GitHub_M
Reserved: 26.05.2026 Published: 18.06.2026 Updated: 18.06.2026

pam_usb provides hardware authentication for Linux using removable media. In pam_usb 0.9.1 and earlier, usb_get_process_parent_id() can cause an infinite loop DoS because it does not initialize *ppid on failure. In pusb_local_login(), the same variable is reused as input and output in a process-tree while loop; if /proc/<pid>/stat cannot be read (for example, when an ancestor process exits during authentication), the PID is not updated and the loop does not terminate. This hangs the authenticating process (such as sudo, sshd, or login) until it is forcibly terminated. This issue has been fixed in version 0.9.2.

Metrics

CVSS Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 4.7

Product Status

Vendor mcdope
Product pam_usb
Versions
  • Version < 0.9.2 is affected

References

Problem Types

  • CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') CWE