GHSA-6gqr-mx34-wh8r CVE-2026-41325
Kirby is vulnerable to authorization bypass during page, file and user creation via blueprint injection
- Severity
- 0.0 / 10
- High · CVSS 4.0
- Exploit chance (EPSS)
- 0.36%
- Chance of exploitation in the next 30 days. Higher than 30.14% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-863 Incorrect Authorization
- Fix
4.9.0- Upgrade getkirby/cms to this version or later
Description
TL;DR
This vulnerability affects all Kirby sites where users of a particular role have no permission to create pages, files or users (pages.create, files.create or users.create permission is disabled). This can be due to configuration in the user blueprint(s), via options in the model blueprint(s) or via a combination of both settings.
This vulnerability is of high severity for affected sites.
Developers' Kirby sites are not affected if they intend all users of their site to be able to create pages, files and users. The vulnerability can only be exploited by authenticated users.
Introduction
An authorization bypass allows authenticated users to perform actions they should not be allowed to perform based on their configured permissions, thereby causing a privilege escalation.
The effects of an authorization bypass can include unauthorized access to sensitive information as well as unauthorized changes to content or system information.
Impact
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. In affected releases, 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.
Patches
The problem has been patched in Kirby 4.9.0 and Kirby 5.4.0. Please update to one of these or a later version to fix the vulnerability.
In all of the mentioned releases, we 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.
Credits
Kirby thanks @offset for responsibly reporting the identified issue.
Affected versions
Packagist
| Package | Vulnerable | Fixed in |
|---|---|---|
| getkirby/cms | < 4.9.0 |
4.9.0 |
| getkirby/cms | >= 5.0.0, < 5.4.0 |
5.4.0 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
getkirby/cms Packagist → 4.9.0
- composer
composer require getkirby/cms:^4.9.0
Severity breakdown
CVSS 4.0 0.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- None
- Privileges required
- Low
- User interaction
- None
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- High
- Availability (vulnerable system)
- None
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
CVSS 3.1 8.8
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Weakness
CWE-863: Incorrect Authorization
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
How to prevent it
- Architecture and Design: Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
- Architecture and Design: Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor [REF-7].
- Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
- Architecture and Design: For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page. One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.
- System Configuration, Installation: Use the access control capabilities of your operating system and server environment and define your access control lists accordingly. Use a "default deny" policy when defining these ACLs.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-9vx2-j98c-p72w Kirby: Access to image files and limited access to JSON files outside of the site root via path traversal in the media handling | High | Also affects getkirby/cms |
| GHSA-6j4c-mgqr-qv76 Kirby: Access to image files outside of the site root via path traversal in the media handling | Medium | Also affects getkirby/cms |
| GHSA-67mx-6wf2-92xp Kirby: File upload permissions are not checked during processing of chunk data | High | Also affects getkirby/cms |
| GHSA-rf2p-vh74-7vvh Kirby: System path exposure from error messages in the REST API | Medium | Also affects getkirby/cms |
| GHSA-r3w8-2c5r-h9j9 Kirby: `pages.access` permission is not checked in the `site/find` REST API route | High | Also affects getkirby/cms |
| GHSA-89cp-7p28-jffg Kirby: Access to files of top-level drafts is not protected by permissions | Medium | Also affects getkirby/cms |
| GHSA-whxw-24jc-cwmv Kirby: External Initialization of the Panel on reverse proxy setups with the `Forwarded` header | Critical | Also affects getkirby/cms |
| GHSA-wr9h-4r83-f4v6 Kirby: Cross-site scripting (XSS) from incomplete HTML/XML sanitization in `Dom::sanitize()` | High | Also affects getkirby/cms |
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