CVE-2018-14599: Canonical Ubuntu Linux

Critical severity, CVSS 9.8. EPSS: 4.8% chance of exploitation in the next 30 days.

An issue was discovered in libX11 through 1.6.5. The function XListExtensions in ListExt.c is vulnerable to an off-by-one error caused by malicious server responses, leading to DoS or possibly unspecified other impact.

Affected products

• Canonical Ubuntu Linux: version 12.04 only; version 14.04 only; version 16.04 only; version 18.04 only
• Debian Debian Linux: version 8.0 only
• Fedoraproject Fedora: version 28 only
• Red Hat Enterprise Linux Desktop: version 7.0 only
• Red Hat Enterprise Linux Server: version 7.0 only
• Red Hat Enterprise Linux Workstation: version 7.0 only
• X.org LIBX11: up to and including 1.6.5

Published 2018-08-24. Last modified 2026-06-17.