pam_usb: Unchecked integer multiplication before xmalloc() in conf.c allows heap-based buffer overflow on 32-bit targets

published 2026-05-27 5 mo ago modified 2026-10-26 13 d ago also EUVD-2026-32649

cvss: 6.7; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.1%; EPSS 0.1% chance of exploitation in 30 days, percentile 4%
public exploits: 0; none known

pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.1, src/conf.c allocates heap memory proportional to n_devices, a count derived from libxml2 XPath evaluation of the config file, without first enforcing an upper bound. On 32-bit targets (armv7l, i686 -- both listed in the project Makefile), the multiplication n_devices * sizeof(t_pusb_device) wraps around size_t, causing xmalloc() to receive a very small size. Because xmalloc() only calls abort() on NULL return, a small-but-non-NULL allocation is accepted, and subsequent array writes overflow the heap. This vulnerability is fixed in 0.9.1.

CISA SSVC

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

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.7	CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Affected products

mcdope pam_usb

Classification

Weakness

CWE-122 Heap-based Buffer Overflow
CWE-190 Integer Overflow or Wraparound

References

Sources

CVE List CVE-2026-48065
NVD CVE-2026-48065

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary