NULL pointer dereference in Php

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.

EPSS: 0.009 (57.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-6491?
CVE-2025-6491 is a medium-severity vulnerability in Php, classified under NULL Pointer Dereference. CVSS score: 5.9/10. Published 2025-07-13.
How severe is CVE-2025-6491?
Medium severity. CVSS v3 base score is 5.9 out of 10.
Is CVE-2025-6491 known to be exploited?
2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.