CVE-2026-48066

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

State: Published
Severity: 5.7 Medium
Published: May 27, 2026
Updated: May 28, 2026
Reserved: May 20, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	5.7 Medium	CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H	GitHub_M

Weaknesses

CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-476 NULL Pointer Dereference

Affected Products

Product	Versions
pam_usbmcdope	< 0.9.1Affected

References

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