CVE-2026-48986
pam_usb: Infinite loop DoS in process-tree walk when parent process exits during authentication
Description
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.
CVSS Vector Breakdown
AV:LAttack VectorAC:HAttack ComplexityPR:LPrivileges RequiredUI:NUser InteractionS:UScopeC:NConfidentialityI:NIntegrityA:HAvailabilityWeaknesses
Affected Products
Attack Graph
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Exploitability
MITRE ATT&CK
1 techniqueReferences
Timeline
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