CVE-2025-6491

MEDIUM
Published Jul 13, 2025 Modified Nov 4, 2025 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.

Is your site exposed to CVE-2025-6491?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

5.9
MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor Product
php php
php php
php php
php php

References

Frequently Asked Questions

What is CVE-2025-6491? +
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. It has a CVSS v3.1 base score of 5.9 (MEDIUM).
How severe is CVE-2025-6491? +
CVE-2025-6491 has a CVSS v3.1 score of 5.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.
What products are affected by CVE-2025-6491? +
CVE-2025-6491 affects products from php, specifically: php. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2025-6491? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

Don't wait for an exploit

Scan your website for vulnerabilities like CVE-2025-6491 — free, no signup required.