Vulnerability · Published May 27, 2026 · Assigned by GitHub_M

CVE-2026-44709pam_usb: PINENTRY_FALLBACK_APP environment variable allows arbitrary command execution

High 7.8

In plain English

A high-severity OS command injection in pam_usb from mcdope. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 4% of all known vulnerabilities).

Severity (CVSS 3.1)7.8High

Exploit odds (30 days)0.2%top 95.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
mcdope	pam_usb	< 0.8.7

Weakness: CWE-78 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

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