What’s Vulnerable › Vulnerabilities

CVE-2025-6491: NULL Pointer Dereference in PHP SOAP Extension via Large XML Namespace Prefix

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2025-07-13 · updated 2026-06-17
• Weakness: CWE-476

Description

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: from 8.1.0 before 8.1.33; from 8.2.0 before 8.2.29; from 8.3.0 before 8.3.23; from 8.4.0 before 8.4.10 — fixed in 8.1.33, 8.2.29, 8.3.23, 8.4.10

How to fix

Upgrade to a fixed version: PHP 8.1.33, 8.2.29, 8.3.23, 8.4.10. Check the vendor advisory for mitigations.

References

• https://github.com/php/php-src/security/advisories/GHSA-453j-q27h-5p8x
• http://www.openwall.com/lists/oss-security/2025/07/11/4
• https://lists.debian.org/debian-lts-announce/2025/07/msg00017.html
• https://github.com/php/php-src/security/advisories/GHSA-453j-q27h-5p8x

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