CVE-2026-44709CWE-78

pam_usb: PINENTRY_FALLBACK_APP environment variable allows arbitrary command execution

High · published May 27, 2026

CVSS v3.1
7.8
EPSS
0%
Percentile
10.8
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
7.8 · HIGH
Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00211 · 10.8th percentile
Weakness
CWE-78 · Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Published
2026-05-27T20:20Z
EPSS history
Timeline
  • 27 MAY 20:20Z
    pam_usb: PINENTRY_FALLBACK_APP environment variable allows arbitrary command execution
    cvelistv5