CVE-2011-4539: Canonical Ubuntu Linux

Medium severity, CVSS 5.0. EPSS: 15.2% chance of exploitation in the next 30 days.

dhcpd in ISC DHCP 4.x before 4.2.3-P1 and 4.1-ESV before 4.1-ESV-R4 does not properly handle regular expressions in dhcpd.conf, which allows remote attackers to cause a denial of service (daemon crash) via a crafted request packet.

Affected products

• Canonical Ubuntu Linux: version 11.04 only; version 11.10 only
• Debian Debian Linux: version 6.0 only; version 7.0 only
• ISC Dhcp: version 4.0 only; version 4.0.0 only; version 4.0.1 only; version 4.0.2 only; version 4.0.3 only; version 4.1.1 only; …

Published 2011-12-08. Last modified 2026-06-16.