high CVSS 7.5 EPSS 0.35%

CVE-2026-7263·PHP vulnerability

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.

Severity
high
Software
PHP
Fixed in
8.5.6
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at 0.35% — higher than 28% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2026-7263 scores 7.5 on CVSS, so a successful attack would be serious — but at 0.35%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

From: 8.5.0

Until: 8.5.6

Fixed in: 8.5.6

How to fix this CVE

Update PHP to version 8.5.6 or later to resolve a denial-of-service vulnerability in the DOMNode::C14N() method that can trigger infinite loops during XML canonicalization. Organizations running PHP 8.5.0–8.5.5 should prioritize this update to prevent application hangs caused by malformed XML processing.

sudo dnf update php php-cli php-common

Defensia detects this vulnerability

How to check if you are affected

  1. Check installed PHP version: php -v | grep -i 'PHP 8.5' and confirm the version is below 8.5.6
  2. Identify XML processing dependencies: grep -r 'DOMNode\|SimpleXML\|xml_parse' /var/www/ to locate code using DOM canonicalization
  3. Review PHP error logs for repeated DoS patterns: tail -f /var/log/php-fpm.log | grep -i 'timeout\|infinite\|loop' and check apache2/nginx error logs for hung requests
  4. Verify patch installation: php -v should display version 8.5.6 or higher, and dpkg -l | grep php or rpm -qa | grep php should show updated package timestamps

FAQ

What is CVE-2026-7263?

CVE-2026-7263 is a denial-of-service vulnerability in PHP's DOMNode::C14N() method that creates circular references in XML data structures during canonicalization, causing subsequent XML operations to hang indefinitely and exhaust server resources.

Is CVE-2026-7263 being actively exploited?

No, CVE-2026-7263 is not listed in CISA's Known Exploited Vulnerabilities catalog, and no public exploits are currently available.

What versions of PHP are affected by CVE-2026-7263?

PHP versions 8.5.0 through 8.5.5 are vulnerable; version 8.5.6 and later contain the fix.

How do I check if my server is vulnerable to CVE-2026-7263?

Run php -v and check if the version is between 8.5.0 and 8.5.5. If so, your server is vulnerable and requires immediate patching.

Does Defensia detect CVE-2026-7263?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If PHP is installed on a monitored server, CVE-2026-7263 will appear in your dashboard with remediation steps.

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References

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