CVE-2011-4539

CVE-2011-4539 is a none vulnerability published on December 8, 2011. 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.

CVE-2011-4539 was first published in the National Vulnerability Database on December 8, 2011, with the most recent update on April 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

CVE-2011-4539 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 96.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2011-4539, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.