CVE-2026-48981 | pam_usb provides hardware authentication for Linux using ord… | CVSS 6.7 MEDIUM

Description

pam_usb provides hardware authentication for Linux using ordinary removable media. In versions prior to 0.9.2, pam_usb calls xmlReadFile() with flags=0 when loading the configuration file, allowing libxml2 to process external entity references (XXE), potentially making outbound network connections or local file reads at XML parse time from the context of the authenticating process. The vulnerability requires the configuration file to contain crafted XML entity references. Since pam_usb.conf is root-owned, direct exploitation requires prior write access to the config, but the defence-in-depth impact is significant given that pam_usb.so runs in setuid contexts (sudo, su). This issue has been fixed in version 0.9.2.

Metadata

CVE ID: CVE-2026-48981
State: PUBLISHED
Assigner: GitHub_M
Reserved: 2026-05-26 23:26 UTC
Published: 2026-06-18 18:55 UTC
Last updated: 2026-06-18 18:55 UTC
Primary CWE: CWE-611
CWE-611: Improper Restriction of XML External Entity Referen…
Vendor / Product: mcdope / pam_usb
Sources: cve.org · NVD

Severity & Metrics

6.7 MEDIUM CVSS 3.1

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:L/A:L

Affected products (1)

Vendor	Product	Platform	Versions
mcdope	pam_usb	—	< 0.9.2

Weakness (CWE)

CWE	Source	Description
CWE-611	cna	CWE-611: Improper Restriction of XML External Entity Reference

CVSS scores (1)

Score	Severity	Version	Source	Vector
6.7	MEDIUM	3.1	cna	CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:L/A:L

References (2)

https://github.com/mcdope/pam_usb/security/advisories/GHSA-96vv-r4wc-28c2 https://github.com/mcdope/pam_usb/security/advisories/GHSA-96vv-r4wc-28c2
https://github.com/mcdope/pam_usb/releases/tag/0.9.2 https://github.com/mcdope/pam_usb/releases/tag/0.9.2