A vulnerability classified as problematic was found in Kirby up to 3.5.8.2/3.6.6.2/3.7.5.1/3.8.4.0/3.9.5. This vulnerability affects the function Data::decode/Xml::parse. The manipulation with an unknown input leads to a xml entity expansion vulnerability. The CWE definition for the vulnerability is CWE-776. The product uses XML documents and allows their structure to be defined with a Document Type Definition (DTD), but it does not properly control the number of recursive definitions of entities. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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 Kirby 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.

The weakness was released 07/27/2023 as GHSA-q386-w6fg-gmgp. The advisory is shared for download at github.com. This vulnerability was named CVE-2023-38490 since 07/18/2023. There are known technical details, but no exploit is available.

Upgrading to version 3.5.8.3, 3.6.6.3, 3.7.5.2, 3.8.4.1 or 3.9.6 eliminates this vulnerability. Applying the patch 277b05662d2b67386f0a0f18323cf68b30e86387 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

Entries connected to this vulnerability are available at VDB-235574, VDB-235575, VDB-235578 and VDB-235579.

Productinfo

Name

• Kirby

Version

• 3.5.8.0
• 3.5.8.1
• 3.5.8.2
• 3.6.6.0
• 3.6.6.1
• 3.6.6.2
• 3.7.5.0
• 3.7.5.1
• 3.8.0
• 3.8.1
• 3.8.2
• 3.8.3
• 3.8.4
• 3.9.0
• 3.9.1
• 3.9.2
• 3.9.3
• 3.9.4
• 3.9.5

License

• open-source

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