CVE-2009-4418: PHP

Medium severity, CVSS 5.0. EPSS: 1% chance of exploitation in the next 30 days.

The unserialize function in PHP 5.3.0 and earlier allows context-dependent attackers to cause a denial of service (resource consumption) via a deeply nested serialized variable, as demonstrated by a string beginning with a:1: followed by many {a:1: sequences.

Affected products

• PHP PHP: up to and including 5.3.0; version 5 only; version 5.0 only; version 5.0.0 only; version 5.0.1 only; version 5.0.2 only; …

Published 2009-12-24. Last modified 2026-06-16.