CVE-2025-6491: PHP

Medium severity, CVSS 5.9. EPSS: 1% chance of exploitation in the next 30 days.

In PHP versions:8.1.* before 8.1.33, 8.2.* before 8.2.29, 8.3.* before 8.3.23, 8.4.* before 8.4.10 when parsing XML data in SOAP extensions, overly large (>2Gb) XML namespace prefix may lead to null pointer dereference. This may lead to crashes and affect the availability of the target server.

Affected products

• PHP PHP: from 8.1.0, before 8.1.33 (fixed in 8.1.33); from 8.2.0, before 8.2.29 (fixed in 8.2.29); from 8.3.0, before 8.3.23 (fixed in 8.3.23); from 8.4.0, before 8.4.10 (fixed in 8.4.10)

Published 2025-07-13. Last modified 2026-06-17.