Vulnerability · Published May 27, 2026 · Assigned by GitHub_M

CVE-2026-44713pam_usb: Command injection via $TMUX environment variable leads to RCE as root

High 8.8

In plain English

A high-severity OS command injection in pam_usb from mcdope. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 5% of all known vulnerabilities).

Severity (CVSS 3.1)8.8High

Exploit odds (30 days)0.2%top 95.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
mcdope	pam_usb	< 0.8.7

Weakness: CWE-78, CWE-116 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

References

https://github.com/mcdope/pam_usb/security/advisories/GHSA-822m-whrh-vrj8 x_refsource_CONFIRM