pam_usb: NULL pointer dereference from UDisks device fields causes PAM crash and login denial-of-service

published 2026-05-27 5mo ago modified 2026-10-26 14d ago also EUVD-2026-32660

cvss: 4.6; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits: 0; none known

pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.8.7, src/device.c passed the return values of udisks_drive_get_serial(), udisks_drive_get_vendor(), and udisks_drive_get_model() directly to strcmp() without NULL checks. The GIO/UDisks API documentation states these accessors can return NULL for devices that do not expose the corresponding field. Passing NULL to strcmp() is undefined behaviour (typically a SIGSEGV). This vulnerability is fixed in 0.8.7.

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CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 5mo ago (2026-05-28)

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
CNA	3.1	4.6	CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

mcdope pam_usb

Classification

Weakness

CWE-476 NULL Pointer Dereference

References

github.com /mcdope/pam_usb/security/advisories/GHSA-j8cq-2gv6-gfwf

Sources

CVE List CVE-2026-44710
NVD CVE-2026-44710

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