CVE-2018-7548: Canonical Ubuntu Linux

Critical severity, CVSS 9.8. EPSS: 2.5% chance of exploitation in the next 30 days.

In subst.c in zsh through 5.4.2, there is a NULL pointer dereference when using ${(PA)...} on an empty array result.

Affected products

• Canonical Ubuntu Linux: version 17.10 only
• Zsh Zsh: up to and including 5.4.2

Published 2018-02-27. Last modified 2026-06-17.