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CVE-2026-54002

Cross-Site Scripting (XSS) in getkirby/cms (CVE-2026-54002)

Summary

Cross-site scripting in getkirby/cms (CVE-2026-54002). Risk of unauthorized operations or information disclosure. Exploitable via writer. Mitigation: upgrade to 5.4.4 or later.

Original description

The description as published by the source.

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 harmful script can, for example, trigger requests to Kirby's API with the permissions of the victim.

In a stored XSS attack, the malicious payload is saved into the content data and has the potential to affect other users or site visitors.

Such vulnerabilities are critical if you might have potential attackers in your group of authenticated Panel users. They can escalate their privileges if they get access to the Panel session of an admin user. De…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-54002 has been found in getkirby/cms.
Attackers can target a specific entry point like writer over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade getkirby/cms to 5.4.4 or later.
If unsure, ask your IT team or search "getkirby/cms CVE-2026-54002" on the vendor's site.

CVE-2026-54002 (getkirby/cms) — CWE-79
Attack surface: writer / list / Sane
Patched: 5.4.4 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

Cross-site scripting (XSS) (CWE-79) exists in getkirby/cms. Attackers reach the vulnerable code path via writer.

📍 Affected scope

Check the vendor advisory for the affected versions of getkirby/cms. Attack surface: writer / list / Sane.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 5.4.4.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'getkirby/cms' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'getkirby/cms' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で getkirby/cms を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade getkirby/cms to 5.4.4

    ステージング環境で 5.4.4 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

composer getkirby/cms
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.4"}]}]
Packagist getkirby/cms
[{"type":"ECOSYSTEM","events":[{"introduced":"5.0.0-alpha.1"},{"fixed":"5.4.4"}]}]

References

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