CVE-2026-21896

Published Jan 8, 2026

Last updated 3 months ago

CVSS medium 5.8

Overview

Description
Kirby is an open-source content management system. From versions 5.0.0 to 5.2.1, Kirby is missing permission checks in the content changes API. This vulnerability affects all Kirby sites where user permissions are configured to prevent specific role(s) from performing write actions, specifically by disabling the update permission with the intent to prevent modifications to site content. This vulnerability does not affect those who have not altered the deviated from default user permissions. This issue has been patched in version 5.2.2.
Source
security-advisories@github.com
NVD status
Analyzed
Products
kirby

Risk scores

CVSS 4.0

Type
Secondary
Base score
5.8
Impact score
-
Exploitability score
-
Vector string
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Severity
MEDIUM

CVSS 3.1

Type
Primary
Base score
5.7
Impact score
3.6
Exploitability score
2.1
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N
Severity
MEDIUM

Weaknesses

security-advisories@github.com
CWE-863

Social media

Hype score
Not currently trending

Configurations

Related CVEs

  1. Kirby is an open-source content management system. 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. Kirby provides the `pages.create`, `files.create` and `users.create` permissions (among others). These permissions can again be set in the user blueprint and/or in the blueprint of the target model via `options`. Prior to versions 4.9.0 and 5.4.0, Kirby allowed to override the `options` during the creation of pages, files and users by injecting custom dynamic blueprint configuration into the model data. The injected `options` could include `'create' => true`, which then caused an override of the permissions and options configured by the site developer in the user and model blueprints. The problem has been patched in Kirby 4.9.0 and Kirby 5.4.0. The patched versions have updated the normalization code that is used during the creation of pages, files and users to include a filter for the `blueprint` property. This prevents the injection of dynamic blueprint configuration into the creation request.•CVE-2026-41325
  2. Kirby is an open-source content management system. 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). Prior to versions 4.9.0 and 5.4.0, 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 added a check to the page creation rules that ensures that users without the `pages.changeStatus` permission cannot create published pages, only page drafts.•CVE-2026-40099
  3. 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.•CVE-2026-34587
  4. Kirby is an open-source content management system. Kirby's `Xml::value()` method has special handling for `<![CDATA[ ]]>` blocks. If the input value is already valid `CDATA`, it is not escaped a second time but allowed to pass through. However, prior to versions 4.9.0 and 5.4.0, it was possible to trick this check into allowing values that only contained a valid `CDATA` block but also contained other structured data outside of the `CDATA` block. This structured data would then also be allowed to pass through, circumventing the value protection. The `Xml::value()` method is used in `Xml::tag()`, `Xml::create()` and in the `Xml` data handler (e.g. `Data::encode($string, 'xml')`). Both the vulnerable methods and the data handler are not used in the Kirby core. However they may be used in site or plugin code, e.g. to create XML strings from input data. If those generated files are passed to another implementation that assigns specific meaning to the XML schema, manipulation of this system's behavior is possible. Kirby sites that don't use XML generation in site or plugin code are not affected. The problem has been patched in Kirby 4.9.0 and Kirby 5.4.0. In all of the mentioned releases, Kirby has added additional checks that only allow unchanged `CDATA` passthrough if the entire string is made up of valid `CDATA` blocks and no structured data. This protects all uses of the method against the described vulnerability.•CVE-2026-32870
  5. Kirby CMS through 5.1.4 allows an authenticated user with 'Editor' permissions to cause a persistent Denial of Service (DoS) via a malformed image upload. The application fails to properly validate the return value of the PHP getimagesize() function. When the system attempts to process this file for metadata or thumbnail generation, it triggers a fatal TypeError.•CVE-2026-29905

References

Sources include official advisories and independent security research.