CVE-2026-44713

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

State: Published
Severity: 8.8 High
Published: May 27, 2026
Updated: May 30, 2026
Reserved: May 7, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	8.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H	GitHub_M

Weaknesses

CWE-78 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
CWE-116 Improper Encoding or Escaping of Output

Affected Products

Product	Versions
pam_usbmcdope	< 0.8.7Affected

References

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

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