CVE-2019-18978: Canonical Ubuntu Linux

Medium severity, CVSS 5.3. EPSS: 2.5% chance of exploitation in the next 30 days.

An issue was discovered in the rack-cors (aka Rack CORS Middleware) gem before 1.0.4 for Ruby. It allows ../ directory traversal to access private resources because resource matching does not ensure that pathnames are in a canonical format.

Affected products

• Canonical Ubuntu Linux: version 16.04 only
• Debian Debian Linux: version 8.0 only; version 9.0 only; version 10.0 only
• Rack-Cors Project Rack-Cors: before 1.0.4 (fixed in 1.0.4)

Published 2019-11-14. Last modified 2026-06-17.