Kirby: Cross-site scripting (XSS) from incomplete HTML/XML sanitization in Dom::sanitize()

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.5 · 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 · score source

EPSS

• CVE-2026-54002: 0.55% estimated exploitation activity in the next 30 days; percentile 45.87 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

TL;DR This vulnerability affects Kirby sites and plugins that use the writer or list fields or that use $dom-sanitize(), Sane::sanitize(), Sane\Html::sanitize(), Sane\Svg::sanitize(), Sane\Xml::sanitize(), Sane::sanitizeFile() or $file-sanitizeContents() with untrusted input. It was possible to inject malicious markup as children of an unknown HTML/XML tag, which would then be passed through Dom::sanitize() without being correctly sanitized according to the provided sanitization rules, causing a cross-site scripting (XSS) risk. This vulnerability is of high severity for affected sites. The default file upload protection is not affected, so sites that only validate uploaded files are not exposed to this vulnerability. The vulnerability can only be exploited by authenticated users. ---- Introduction Cross-site scripting (XSS) is a type of vulnerability that allows executing any kind of JavaScript code inside the site frontend or Panel session of the same or other users. In the Panel, a…

Published by the source

18 Jun 2026, 15:04 UTC

Last modified by the source

18 Jun 2026, 15:04 UTC

Source last checked

26 Oct 2026, 14:49 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-wr9h-4r83-f4v6

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# Patch Next advisory brief: CVE-2026-54002

Advisory: Kirby: Cross-site scripting (XSS) from incomplete HTML/XML sanitization in `Dom::sanitize()`
IDs: CVE-2026-54002, GHSA-wr9h-4r83-f4v6
Record: https://patchnext.com/advisories/cve-2026-54002 (revision 1, source checked 26 Oct 2026, 14:49 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: getkirby/cms 5.4.4, 4.9.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist getkirby/cms: affected <= 4.9.3; >= 5.0.0-alpha.1, <= 5.4.3; fixed in 4.9.4, 5.4.4

## Suggested inspection (read-only)
- Packagist getkirby/cms: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on getkirby/cms.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-wr9h-4r83-f4v6 (GitHub-reviewed advisory GHSA-wr9h-4r83-f4v6 lists affected ranges: Packagist getkirby/cms >=0 =5.0.0-alpha.1 <=5.4.3)

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