CVE-2026-7263: DoS attack via DOMNode::C14N()

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-10 · updated 2026-07-24
Weakness: CWE-404

Description

In PHP versions 8.4.* before 8.4.21 and 8.5.* before 8.5.6, DOMNode::C14N() method may process the XML data incorrectly, causing a circular linked list in the data structure representing the XML document. This may cause subsequent processing of the XML document to enter infinite loop, causing denial of service in the processing application.

Affected products

PHP: from 8.4.0 before 8.4.21; from 8.5.0 before 8.5.6 — fixed in 8.4.21, 8.5.6

How to fix

Upgrade to a fixed version: PHP 8.4.21, 8.5.6. Check the vendor advisory for mitigations.

References

https://github.com/php/php-src/security/advisories/GHSA-4jhr-8w89-j733
https://access.redhat.com/errata/RHSA-2026:22649
https://access.redhat.com/security/cve/CVE-2026-7263
https://bugzilla.redhat.com/show_bug.cgi?id=2468572
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-7263.json

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