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PHPApplication

CVE-2026-7263

HIGH · 7.5 CVSS v3.1 Published 2026-05-10
Fix available
A fix is available. Upgrade to 8.4.21 / 8.5.6 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In PHP versions 8.4.x before 8.4.21 and 8.5.x before 8.5.6, the DOMNode::C14N() method incorrectly processes XML data, creating a circular linked list in the document structure. This causes subsequent XML processing to enter an infinite loop, resulting in denial of service.

MitigationUpgrade PHP to version 8.4.21, 8.5.6, or later. Applications using DOMNode::C14N() should be tested after upgrading to verify XML processing functions correctly.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
PHPApplication
Affected:>= 8.4.0, < 8.4.21>= 8.5.0, < 8.5.6

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed PHP version
    Run `php -v` on the command line or call `phpinfo()` in a script to retrieve the PHP version string
    Affected if The version is 8.4.0 through 8.4.20, or 8.5.0 through 8.5.5 (i.e., it falls within >= 8.4.0, < 8.4.21 or >= 8.5.0, < 8.5.6)
  2. Identify use of DOMNode::C14N method
    Search source code for occurrences of `DOMNode::C14N`, `C14N()`, or `c14n` method calls on DOM nodes
    Affected if The application code invokes the C14N() method on DOMNode objects to canonicalize XML documents
  3. Verify DOM extension is loaded
    Run `php -m | grep -i dom` or check phpinfo() for the 'dom' extension
    Affected if The DOM extension is loaded and the vulnerable C14N method is in use
  4. Review XML processing workflows
    Audit application code that processes XML input and passes documents to DOMNode::C14N()
    Affected if User-supplied or untrusted XML data is being processed through the C14N() method

A user is affected if their PHP version is 8.4.0-8.4.20 or 8.5.0-8.5.5 AND their application uses the DOMNode::C14N() method to process XML documents.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 8.4.21 / 8.5.6 or later
Fixed in 8.4.218.5.6
Interim mitigation

Upgrade PHP to version 8.4.21, 8.5.6, or later. Applications using DOMNode::C14N() should be tested after upgrading to verify XML processing functions correctly.

Recommended fix High confidence

PHP 8.4.21 or later (for 8.4.x branch); PHP 8.5.6 or later (for 8.5.x branch)

  1. 1. Identify the current PHP version by running 'php -v' or 'phpinfo()'
  2. 2. If running PHP >= 8.4.0 and < 8.4.21, plan upgrade to version 8.4.21 or later
  3. 3. If running PHP >= 8.5.0 and < 8.5.6, plan upgrade to version 8.5.6 or later
  4. 4. For systems using package managers (apt, yum, dnf), update via: 'sudo apt update && sudo apt upgrade php*' or 'sudo dnf update php*'
  5. 5. For systems using Composer, update PHP binary or container images to the fixed version
  6. 6. After upgrade, verify the new version: 'php -v'
  7. 7. Test that PHP applications including DOM/XML processing function correctly
  8. 8. Monitor for any regressions and consult PHP 8.4.21 or 8.5.6 release notes if needed
Caveat Standard minor version upgrade risk - review 8.4.21 and 8.5.6 release notes for any deprecation notices

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in PHP Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,570
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-7263 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data