Vulnerability · Published Jun 18, 2026 · Assigned by GitHub_M

CVE-2026-48981pam_usb: xmlReadFile flags=0 permits XXE network entity fetching in conf.c

Medium 6.7

In plain English

A medium-severity XML external entity in pam_usb from mcdope. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 5% of all known vulnerabilities).

Severity (CVSS 3.1)6.7Medium

Exploit odds (30 days)0.2%top 95.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
mcdope	pam_usb	< 0.9.2

Weakness: CWE-611 · Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:L/A:L

References

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