CVE-2026-44709

pam_usb: PINENTRY_FALLBACK_APP environment variable allows arbitrary command execution

State: Published
Severity: 7.8 High
Published: May 27, 2026
Updated: Jun 2, 2026
Reserved: May 7, 2026

Description

pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.8.7, pamusb-pinentry reads the PINENTRY_FALLBACK_APP environment variable and executes it directly without any validation. Any process that can set environment variables before pamusb-pinentry is invoked can point PINENTRY_FALLBACK_APP at an arbitrary binary or script and have it executed with the privileges of the pam_usb tool chain. This vulnerability is fixed in 0.8.7.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	GitHub_M

Weaknesses

CWE-78 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Affected Products

Product	Versions
pam_usbmcdope	< 0.8.7Affected

References

https://github.com/mcdope/pam_usb/security/advisories/GHSA-jxrj-q67x-wr4c

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