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pam_usb: NULL Dereference Crash in pusb_is_loginctl_local when loginctl Returns Empty Remote Field

Published Jun 18, 2026

Description

pam_usb provides hardware authentication for Linux using ordinary removable media. In versions 0.9.1 and below, pusb_is_loginctl_local() can cause a NULL dereference crash when parsing loginctl output. The function calls popen() and reads the result; if the Remote field is only a newline, fgets() succeeds but strtok_r(buf, "\n", &saveptr) returns NULL. A subsequent strcmp(is_remote, "no") then dereferences NULL, causing undefined behavior (typically SIGSEGV) and crashing the PAM module. This can crash the authenticating process (e.g., sudo, login) and, depending on PAM stack configuration, deny access for all users of the affected service. This issue has been fixed in version 0.9.2.

Affected products

Remediation

No remediation recorded yet.

References (3)

Change history (0)

No recorded changes yet.

Sources

CVE.org / MITRE

Status PUBLISHED
Assigner GitHub_M
Published Jun 18, 2026
Updated Jun 18, 2026
Reserved May 26, 2026

CISA Vulnrichment

Updated Jun 18, 2026

NVD

Status Deferred
Modified Jun 22, 2026

Red Hat

No data

ENISA EUVD

Assigner GitHub_M
Published Jun 18, 2026
Updated Jun 18, 2026

GitHub

No data