CVE-2026-44713CWE-116CWE-78

pam_usb: Command injection via $TMUX environment variable leads to RCE as root

High · published May 27, 2026

CVSS v3.1
8.8
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, src/tmux.c reads the user's $TMUX environment variable, splits it on commas, and interpolates the socket-path component directly into a shell command passed to popen(). Because the value is placed inside double-quotes without sanitisation, any value containing " terminates the quoted string and injects arbitrary shell syntax. popen() runs as root inside the PAM stack. This vulnerability is fixed in 0.8.7.

The record
Technical detail
CVSS v3.1
8.8 · HIGH
Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00211 · 10.8th percentile
Weaknesses
CWE-116 · Improper Encoding or Escaping of Output; CWE-78 · Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Published
2026-05-27T20:13Z
EPSS history
Timeline
  • 27 MAY 20:13Z
    pam_usb: Command injection via $TMUX environment variable leads to RCE as root
    cvelistv5