Kirby is an open-source content management system. Versions prior to 4.9.1 and 5.4.1 do not check the `pages.access` permission during page draft rendering. Permissions are defined for each user role in the user blueprint (site/blueprints/users/...). It is also possible to customize the permissions for each target model in the model blueprints (such as in site/blueprints/pages/...) using the options feature. The permissions and options together control the authorization of user actions. Kirby provides the pages.access and pages.list permissions (among others). The list permission controls whether affected models appear in lists throughout the Panel and REST API. The access permission has the same effect but also disables direct access to the affected models. This vulnerability affects the path resolver for the main CMS router. The resolver takes an input path from the requested URL and determines which model (page or file) should be rendered. When a path is requested that points to a page draft, the resolver checks that the request either contains a valid preview token or is authenticated by a valid user. In affected releases, Kirby allowed page drafts to be rendered if any valid user was authenticated, even if that user did not have access to the specific page model. Authenticated attackers with knowledge of the full path to an existing page draft could then access the rendered frontend page. This could lead to the disclosure of sensitive information, e.g. ahead of the launch of a new product or post. This issue has been fixed in versions 4.9.1 and 5.4.1.

Kirby is an open-source content management system. In versions prior to 4.9.1 and 5.4.1, the content-locking feature returned lock information without checking the requesting user's access permissions. Kirby's Panel includes a content-locking feature that records which user currently has a model open for editing. This lock prevents conflicting edits by multiple users and displays the locking user's identity in the Panel UI so other users know who to contact. Internally, the locking user's email address and identifier are included in every Panel view payload and in error responses returned when a user attempts to edit a model that is currently locked by another user. This allowed a low-privilege authenticated Panel user, whose role was configured with users.access: false or users.list: false, to learn the email address and identifier of any user who currently had a model open for editing in the Panel, including administrators and other higher-privilege users. Content locks are active for a configurable window (10 minutes by default). The email address can allow admin account enumeration, target phishing, and feed credential-stuffing attacks against the Kirby installation or other sites. The internal user ID can be cross-referenced with other endpoints once the requester has obtained a higher privilege through unrelated means. This issue has been fixed in versions 4.9.1 and 5.4.1.

Kirby is an open-source content management system. In versions prior to 4.9.1 and 5.4.1, Kirby did not securely sanitize the contents of the list field on save, leaving it vulnerable to cross-site scripting (XSS). Kirby's list field stores its formatted content as HTML, and unlike other field types, its HTML special characters cannot be escaped without losing the formatting. Sanitization was only enforced client-side in the Panel, while the server did not sanitize the content on save. As a result, an attacker could bypass the Panel and send malicious HTML directly to Kirby's API, storing unsanitized markup in the content file. That markup would then be rendered on the site frontend and executed in the browsers of site visitors and logged-in users browsing the site, resulting in persistent XSS. This issue has been fixed in versions 4.9.1 and 5.4.1.