CVE-2017-18206: Canonical Ubuntu Linux

Critical severity, CVSS 9.8. EPSS: 3.1% chance of exploitation in the next 30 days.

In utils.c in zsh before 5.4, symlink expansion had a buffer overflow.

Affected products

• Canonical Ubuntu Linux: version 14.04 only; version 16.04 only; version 17.10 only
• Zsh Zsh: before 5.4 (fixed in 5.4)

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