getkirby up to 4.8.x/5.3.x special elements used in a template engine

Summaryinfo

A vulnerability has been found in getkirby kirby up to 4.8.x/5.3.x and classified as critical. Affected by this vulnerability is an unknown functionality. Performing a manipulation results in improper neutralization of special elements used in a template engine. This vulnerability is identified as CVE-2026-34587. The attack can be initiated remotely. There is not any exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as critical has been found in getkirby kirby up to 4.8.x/5.3.x. This affects an unknown part. The manipulation with an unknown input leads to a improper neutralization of special elements used in a template engine vulnerability. CWE is classifying the issue as CWE-1336. The product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Kirby is an open-source content management system. Prior to versions 4.9.0 and 5.4.0, Kirby's user permissions control which user role is allowed to perform specific actions to content models in the CMS. These permissions are defined for each 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. For pages, Kirby provides the `pages.create` and `pages.changeStatus` permissions (among others). In affected releases, Kirby checked these permissions independently and only for the respective action. However the `changeStatus` permission didn't take effect on page creation. New pages are created as drafts by default and need to be published by changing the page status of an existing page draft. This is ensured when the page is created via the Kirby Panel. However the REST API allows to override the `isDraft` flag when creating a new page. This allowed authenticated attackers with the `pages.create` permission to immediately create published pages, bypassing the normal editorial workflow. The problem has been patched in Kirby 4.9.0 and Kirby 5.4.0. Kirby has updated the `Options` logic to no longer double-resolve queries in option values coming from `OptionsQuery` or `OptionsApi` sources. Kirby now only resolves queries that are directly configured in the blueprints.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-34587 since 03/30/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1221 according to MITRE ATT&CK.

Upgrading to version 4.9.0 or 5.4.0 eliminates this vulnerability. The upgrade is hosted for download at github.com.

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Productinfo

Vendor

• getkirby

Name

• kirby

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 5.0
• 5.1
• 5.2
• 5.3

Website

• Product: https://github.com/getkirby/kirby/

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