CVE-2025-6491

NULL Pointer Dereference in PHP SOAP Extension via Large XML Namespace Prefix

MEDIUM

5.9

CVSS Score

Published: July 13, 2025 at 10:10 PM UTC

Updated: June 17, 2026 at 10:02 AM UTC

1 product affected across 1 vendorPHP

Using PHP by PHP Group?

Get instant alerts when new vulnerabilities affect PHP - before attackers find them.

Real-time alertsTrack your software stackFree plan available

Start Free Sign In

Severity

MEDIUM5.9

Exploit prediction

EPSS 1%

SSVC

PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

PHP · PHPdrupal

95%

8.1.* ≤ v < 8.1.338.1.0 ≤ v < 8.1.338.2.* ≤ v < 8.2.298.2.0 ≤ v < 8.2.298.3.* ≤ v < 8.3.238.3.0 ≤ v < 8.3.238.4.* ≤ v < 8.4.108.4.0 ≤ v < 8.4.108.1.*8.2.*8.3.*8.4.*

Affected range stops below 8.1.33, so it looks safe — our inference, not a vendor statement

Affected range stops below 8.2.29, so it looks safe — our inference, not a vendor statement

Affected range stops below 8.3.23, so it looks safe — our inference, not a vendor statement

Affected range stops below 8.4.10, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://github.com/php/php-src/security/advisories/GHSA-453j-q27h-5p8x

References (3)

ExploitVendor Advisory

Source: [email protected]

https://github.com/php/php-src/security/advisories/GHSA-453j-q27h-5p8x

Source: af854a3a-2127-422b-91ae-364da2661108

http://www.openwall.com/lists/oss-security/2025/07/11/4

Source: af854a3a-2127-422b-91ae-364da2661108

https://lists.debian.org/debian-lts-announce/2025/07/msg00017.html

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.9MEDIUMphp

Attack Vector: NETWORK
Complexity: HIGH
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-476

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Create account Sign in

Free plan, no card