CVE-2006-0459: Westes Flex

High severity, CVSS 7.5. EPSS: 4.7% chance of exploitation in the next 30 days.

flex.skl in Will Estes and John Millaway Fast Lexical Analyzer Generator (flex) before 2.5.33 does not allocate enough memory for grammars containing (1) REJECT statements or (2) trailing context rules, which causes flex to generate code that contains a buffer overflow that might allow context-dependent attackers to execute arbitrary code.

Affected products

• Westes Flex: up to and including 2.5.32

Published 2006-03-29. Last modified 2026-06-16.