Summary
Kirby has XML injection in its XML creator toolkit
TL;DR
This vulnerability only affects Kirby sites that use the Xml data handler (e.g. Data::encode($string, 'xml')) or the Xml::create(), Xml::tag() or Xml::value() method(s) in site or plugin code. The Kirby core does not use any of the affected methods.
If consumers use an affected method and cannot rule out input to these methods controlled by an attacker, Kirby strongly recommends that they update to a patch release.
Introduction
XML strings contain structured data in tags and attributes. Depending on the used XML schema, this data can carry specific meaning that can lead to actions in other systems that parse and act on the XML data. Tags and attributes are detected based on their specific syntax, which includes characters such as <, >, ", and &. If these characters are to be used verbatim in text within the XML string, they can be escaped using a <![CDATA[ ]]> block.
XML injection is an attack on a system generating or parsing XML files. By injecting special characters into input data, XML output with a malicious meaning could be generated by a vulnerable system.
Credits
Kirby thanks to Patrick Falb (@dapatrese) at FORMER 03 for responsibly reporting the identified issue.
Impact
Kirby's Xml::value() method has special handling for <![CDATA[ ]]> blocks. If the input value is already valid CDATA, it is not escaped a second time but allowed to pass through. However it was possible to trick this check into allowing values that only contained a valid CDATA block but also contained other structured data outside of the CDATA block. This structured data would then also be allowed to pass through, circumventing the value protection.
The Xml::value() method is used in Xml::tag(), Xml::create() and in the Xml data handler (e.g. Data::encode($string, 'xml')).
Both the vulnerable methods and the data handler are not used in the Kirby core. However they may be used in site or plugin code, e.g. to create XML strings from input data. If those generated files are passed to another implementation that assigns specific meaning to the XML schema, manipulation of this system's behavior is possible.
Kirby sites that don't use XML generation in site or plugin code are not affected.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
The problem has been patched in Kirby 4.9.0 and Kirby 5.4.0. Please update to one of these or a later version to fix the vulnerability.
In all of the mentioned releases, Kirby has added additional checks that only allow unchanged CDATA passthrough if the entire string is made up of valid CDATA blocks and no structured data. This protects all uses of the method against the described vulnerability.
Frequently Asked Questions
- What is CVE-2026-32870? CVE-2026-32870 is a medium-severity security vulnerability in getkirby/cms (composer), affecting versions < 4.9.0. It is fixed in 4.9.0, 5.4.0.
- Which versions of getkirby/cms are affected by CVE-2026-32870? getkirby/cms (composer) versions < 4.9.0 is affected.
- Is there a fix for CVE-2026-32870? Yes. CVE-2026-32870 is fixed in 4.9.0, 5.4.0. Upgrade to this version or later.
- Is CVE-2026-32870 exploitable, and should I be worried? Whether CVE-2026-32870 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-32870 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-32870?
- Upgrade
getkirby/cmsto 4.9.0 or later - Upgrade
getkirby/cmsto 5.4.0 or later
- Upgrade