CVE-2023-38490 is a medium-severity (CVSS 6.8) XML External Entity (XXE) vulnerability in getkirby/cms. A fix is available for getkirby/cms — see the affected versions and patch details below.
Kirby XML External Entity (XXE) vulnerability in the XML data handler
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-38490.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
getkirby/cms🐘getkirby/cms🐘getkirby/cms🐘getkirby/cms🐘getkirby/cmsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
TL;DR
This vulnerability only affects Kirby sites that use the Xml data handler (e.g. Data::decode($string, 'xml')) or the Xml::parse() method in site or plugin code. The Kirby core does not use any of the affected methods.
If you use an affected method and cannot rule out XML input controlled by an attacker, we strongly recommend to update to a patch release.
Introduction
XML External Entities (XXE) is a little used feature in the XML markup language that allows to include data from external files in an XML structure. If the name of the external file can be controlled by an attacker, this becomes a vulnerability that can be abused for various system impacts like the disclosure of internal or confidential data that is stored on the server (arbitrary file disclosure) or to perform network requests on behalf of the server (server-side request forgery, SSRF).
Impact
Kirby's Xml::parse() method used PHP's LIBXML_NOENT constant, which enabled the processing of XML external entities during the parsing operation.
The Xml::parse() method is used in the Xml data handler (e.g. Data::decode($string, 'xml')).
Both the vulnerable method and the data handler are not used in the Kirby core. However they may be used in site or plugin code, e.g. to parse RSS feeds or other XML files. If those files are of an external origin (e.g. uploaded by a user or retrieved from an external URL), attackers may be able to include an external entity in the XML file that will then be processed in the parsing process.
Kirby sites that don't use XML parsing in site or plugin code are not affected.
Patches
The problem has been patched in Kirby 3.5.8.3, Kirby 3.6.6.3, Kirby 3.7.5.2, Kirby 3.8.4.1 and Kirby 3.9.6. Please update to one of these or a later version to fix the vulnerability.
In all of the mentioned releases, we have removed the LIBXML_NOENT constant as processing of external entities is out of scope of the parsing logic. This protects all uses of the method against the described vulnerability.
Credits
Thanks to Alexandre Zanni (@noraj) at ACCEIS and Patrick Falb (@dapatrese) at FORMER 03 for responsibly reporting the identified issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | getkirby/cms | all versions | 3.5.8.3composer require getkirby/cms:^3.5.8.3 |
| 🐘Packagist | getkirby/cms | ≥ 3.6.0&&< 3.6.6.3 | 3.6.6.3composer require getkirby/cms:^3.6.6.3 |
| 🐘Packagist | getkirby/cms | ≥ 3.7.0&&< 3.7.5.2 | 3.7.5.2composer require getkirby/cms:^3.7.5.2 |
| 🐘Packagist | getkirby/cms | ≥ 3.8.0&&< 3.8.4.1 | 3.8.4.1composer require getkirby/cms:^3.8.4.1 |
| 🐘Packagist | getkirby/cms | ≥ 3.9.0&&< 3.9.6 | 3.9.6composer require getkirby/cms:^3.9.6 |
Affected Products
kirbygetkirbyDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getkirby/cms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update getkirby/cms to 3.5.8.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-38490 is resolved across your whole dependency graph.
Workarounds
Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.
Frequently Asked Questions
Is CVE-2023-38490 in your dependencies?
Find it across Packagist, including transitive dependencies.