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

What is CVE-2025-6491?

CVE-2025-6491 is a medium-severity vulnerability in Php Php, published on 13 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-476

Which versions are affected by CVE-2025-6491?

3 open source packages ship an affected version, including libphp, php and php-min. It affects 1 product.

Products include Php Php.

How do I fix CVE-2025-6491?

Upgrade libphp to a fixed version for your release line: 8.1.33, 8.2.29, 8.3.23 or 8.4.10.

Is CVE-2025-6491 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-6491 exists.

Other vulnerabilities in Php Php

• CVE-2012-2688 Integer overflow in n/a Critical 10.0
• CVE-2012-2376 Memory corruption in n/a Critical 10.0
• CVE-2011-3268 Memory corruption in n/a Critical 10.0
• CVE-2009-4143 Other in n/a Critical 10.0
• CVE-2008-5557 Memory corruption in n/a Critical 10.0

All Php Php vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-65118, AZL-65127, BELL-CVE-2025-6491, BIT-libphp-2025-6491, BIT-php-2025-6491, BIT-php-min-2025-6491 and 13 more.