CVE-2009-4142: PHP

Medium severity, CVSS 4.3. EPSS: 6.5% chance of exploitation in the next 30 days.

The htmlspecialchars function in PHP before 5.2.12 does not properly handle (1) overlong UTF-8 sequences, (2) invalid Shift_JIS sequences, and (3) invalid EUC-JP sequences, which allows remote attackers to conduct cross-site scripting (XSS) attacks by placing a crafted byte sequence before a special character.

Affected products

• PHP PHP: up to and including 5.2.11; version 1.0 only; version 2.0 only; version 2.0b10 only; version 3.0 only; version 3.0.1 only; …

Published 2009-12-21. Last modified 2026-06-16.