Kirby up to 3.9.5 Response::file cross site scripting

Summaryinfo

A vulnerability, which was classified as problematic, has been 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 Response::file. This manipulation causes cross site scripting. The identification of this vulnerability is CVE-2023-38491. It is possible to initiate the attack remotely. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Kirby up to 3.5.8.2/3.6.6.2/3.7.5.1/3.8.4.0/3.9.5 and classified as problematic. Affected by this vulnerability is the function Response::file. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. The summary by CVE is:

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 affects all Kirby sites that might have potential attackers in the group of authenticated Panel users or that allow external visitors to upload an arbitrary file to the content folder. Kirby sites are not affected if they don't allow file uploads for untrusted users or visitors or if the file extensions of uploaded files are limited to a fixed safe list. The attack requires user interaction by another user or visitor and cannot be automated. An editor with write access to the Kirby Panel could upload a file with an unknown file extension like `.xyz` that contains HTML code including harmful content like `` tags. The direct link to that file could be sent to other users or visitors of the site. If the victim opened that link in a browser where they are logged in to Kirby and the file had not been opened by anyone since the upload, Kirby would not be able to send the correct MIME content type, instead falling back to `text/html`. The browser would then run the script, which could for example trigger requests to Kirby's API with the permissions of the victim. The issue was caused by the underlying `Kirby\Http\Response::file()` method, which didn't have an explicit fallback if the MIME type could not be determined from the file extension. If you use this method in site or plugin code, these uses may be affected by the same vulnerability. 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 fixed the affected method to use a fallback MIME type of `text/plain` and set the `X-Content-Type-Options: nosniff` header if the MIME type of the file is unknown.

The weakness was shared 07/27/2023 as GHSA-8fv7-wq38-f5c9. It is possible to read the advisory at github.com. This vulnerability is known as CVE-2023-38491 since 07/18/2023. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

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 2f06ba1c026bc91cb0702bc16b7d505642536d15 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.

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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
• 3.8.4.0
• 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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