Vulnerability · Published May 27, 2026 · Assigned by GitHub_M

CVE-2026-48066pam_usb: Thread-unsafe static pointer in log.c causes data race under concurrent PAM authentication

Medium 5.7

In plain English

A medium-severity race condition 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 0.1% (higher than 2% of all known vulnerabilities).

Severity (CVSS 3.1)5.7Medium

Exploit odds (30 days)0.1%top 98.4% 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. Prior to 0.9.1, src/log.c contains a process-wide static pointer that is written on every PAM invocation with the address of a stack-local variable. This violates the PAM re-entrancy requirement and creates a data race when the PAM stack is invoked concurrently from multiple threads. This vulnerability is fixed in 0.9.1.

Affected products (as reported)

Vendor	Product	Versions
mcdope	pam_usb	< 0.9.1

Weakness: CWE-362, CWE-476 · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

References

https://github.com/mcdope/pam_usb/security/advisories/GHSA-qg76-57wq-mpv6 x_refsource_CONFIRM
https://github.com/mcdope/pam_usb/issues/350 x_refsource_MISC
https://github.com/mcdope/pam_usb/issues/55 x_refsource_MISC