CVE-2023-38490
MEDIUMCVE-2023-38490 is a medium-severity (CVSS 6.8) XML External Entity (XXE) vulnerability in getkirby/cms. O3 Security confirms whether CVE-2023-38490 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Kirby XML External Entity (XXE) vulnerability in the XML data handler
Blast Radius
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
Kirby is a content management system. A vulnerability in versions prior to 3.5.8.3, 3.6.6.3, 3.7.5.2, 3.8.4.1, and 3.9.6 only affects Kirby sites that use the Xml data handler (e.g. Data::decode($string, 'xml')) or the Xml::parse() method in site or plugin code. The Kirby core does not use any of the affected methods.
XML External Entities (XXE) is a little used feature in the XML markup language that allows to include data from external files in an XML structure. If the name of the external file can be controlled by an attacker, this becomes a vulnerability that can be abused for various system impacts like the disclosure of internal or confidential data that is stored on the server (arbitrary file disclosure) or to perform network requests on behalf of the server (server-side request forgery, SSRF).
Kirby's Xml::parse() method used PHP's LIBXML_NOENT constant, which enabled the processing of XML external entities during the parsing operation. The Xml::parse() method is used in the Xml data handler (e.g. Data::decode($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.
The problem has been patched in Kirby 3.5.8.3, 3.6.6.3, 3.7.5.2, 3.8.4.1, and 3.9.6. In all of the mentioned releases, the maintainers 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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | getkirby/cms | all versions | 3.5.8.3 |
| 🐘Packagist | getkirby/cms | ≥ 3.6.0&&< 3.6.6.3 | 3.6.6.3 |
| 🐘Packagist | getkirby/cms | ≥ 3.7.0&&< 3.7.5.2 | 3.7.5.2 |
| 🐘Packagist | getkirby/cms | ≥ 3.8.0&&< 3.8.4.1 | 3.8.4.1 |
| 🐘Packagist | getkirby/cms | ≥ 3.9.0&&< 3.9.6 | 3.9.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getkirby/cms. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2023-38490 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2023-38490. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-38490 in your dependencies?
O3 detects CVE-2023-38490 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.