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

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

EPSS (exploitation in 30 days)

0.16% · top 95% of all CVEs (6 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: total

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.8.

Weakness

• CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') (opens in a new tab)All about CWE-78 and its CVEs
• CWE-116: Improper Encoding or Escaping of Output (opens in a new tab)All about CWE-116 and its CVEs

Affected products

• mcdope · pam_usb

  • affected < 0.8.7

References (1)

• https://github.com/mcdope/pam_usb/security/advisories/GHSA-822m-whrh-vrj8 (opens in a new tab)x_refsource_CONFIRM

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-44713](https://trackcve.app/badge/CVE-2026-44713.svg)](https://trackcve.app/cve/CVE-2026-44713)

Record last updated 30 May 2026, 01:48 UTC.