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Not in CISA KEV

Kirby is missing permission checks in the content changes APIGHSA-4j78-4xrm-cr2f

Fix: getkirby/kirby@f5ce134

GHSA-4j78-4xrm-cr2f is a CWE-863 vulnerability in getkirby/cms. A fix is available for getkirby/cms — see the affected versions and patch details below.

Also known asCVE-2026-21896
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-4j78-4xrm-cr2f.

EPSS Exploitation Probability

via FIRST.org ↗
0.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs14th percentile — riskier than 14% of all scored CVEsHighest risk
0.00%0.24%0.49%0.73%0.0%0.2%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected
🐘getkirby/cms

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

TL;DR

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.

If developers haven't configured any user permissions that deviate from the default of allowing all actions, their site is not affected.

Introduction

Kirby allows to restrict the permissions of specific user roles. Users of that role can only perform permitted actions.

Permissions for updating content have already existed and could be configured for each model type, but were not enforced by Kirby's API backend code during operations to the changes version.

The changes version is the content version that contains unsaved changes of existing models (pages, users, files or the site).

Impact

The missing permission checks allowed attackers with Panel access to create or discard a changes version or update the content fields in an existing changes version. All of these actions could affect arbitrary models.

This could cause the following impact:

  • Attackers could maliciously create changes versions for all models of the site, creating editing locks that would prevent other authenticated users from making content changes until those locks were cleared.
  • Attackers could update the content in a malicious way, for example by adding defamatory or spam content or by including malicious links or scripts. While this updated content would not immediately be published to the site, an inattentive editor with update permissions could inadvertently publish these changes in the belief that an authorized user has made them.
  • Attackers could discard extensive changes, making editors lose their content work.

Patches

The problem has been patched in Kirby 5.2.2. Please update to this or a later version to fix the vulnerability.

In the mentioned release, we have added checks for the model update permissions that ensure that users without this permission cannot create, edit or discard the changes version of the respective model.

A future Kirby release will add separate edit and save permissions that will make it possible to control write actions to model content more granularly.

Credits

Thanks to Lukas Kleinschmidt (@lukaskleinschmidt) for responsibly reporting the identified issue.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistgetkirby/cms≥ 5.0.0&&< 5.2.25.2.2composer require getkirby/cms:^5.2.2

Affected Products

1 product · 1 configurations
Application
kirbygetkirby
≥ 5.0.0 && < 5.2.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getkirby/cms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update getkirby/cms to 5.2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4j78-4xrm-cr2f is resolved across your whole dependency graph.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### TL;DR 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. If developers haven't configured any user permissions that deviate from the default of allowing all actions, their site is *not* affected. ---- ### Introduction Kirby allows to restrict the permissions of specific user roles. Users of that role can only perform permitted actions. Permissions for updating content have already existed a
O3 Security · Impact-Aware SCA

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