CVE-2025-6491

Name: CVE-2025-6491
Creator: NVD / NIST
Published: 2025-07-13T22:15:23.353+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.9/10EPSS 0.94%

Last modified Jun 17, 2026

CVE-2025-6491 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. 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.. EPSS estimates a 0.94% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

5.9/10

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

EPSS Probability

0.94%

56.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-476

Affected Software

Vendor	Product	Versions
Php	Php	>= 8.1.0, < 8.1.33
Php	Php	>= 8.2.0, < 8.2.29
Php	Php	>= 8.3.0, < 8.3.23
Php	Php	>= 8.4.0, < 8.4.10

References

https://github.com/php/php-src/security/advisories/GHSA-453j-q27h-5p8xExploit, Vendor Advisory
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-5p8xExploit, Vendor Advisory

Timeline

Published: Jul 13, 2025
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2025-6491?

How severe is CVE-2025-6491?

CVE-2025-6491 has a CVSS score of 5.9/10 (MEDIUM severity). The EPSS model estimates a 0.94% probability of exploitation in the next 30 days.

How do I fix CVE-2025-6491?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-6491?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST