CVE-2006-3251: Hashcash

High severity, CVSS 7.5. EPSS: 3.7% chance of exploitation in the next 30 days.

Heap-based buffer overflow in the array_push function in hashcash.c for Hashcash before 1.21 might allow attackers to execute arbitrary code via crafted entries.

Affected products

• Hashcash Hashcash: up to and including 1.20; version 1.00 only; version 1.01 only; version 1.02 only; version 1.03 only; version 1.04 only; …

Published 2006-06-27. Last modified 2026-06-16.