GHSA-5fhx-9q32-q257
GHSA-5fhx-9q32-q257 is a Cross-site Scripting (XSS) vulnerability in getkirby/cms. O3 Security confirms whether GHSA-5fhx-9q32-q257 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Kirby CMS vulnerable to cross-site scripting (XSS) from list field content in the site frontend
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-5fhx-9q32-q257.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
getkirby/cms🐘getkirby/cmsReal-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 that use the list field or list block, when content is authored by users who may not be fully trusted. The attack requires an authenticated Panel user with update permission to any list field or list block.
This vulnerability is of high severity for affected sites.
Kirby sites are not affected if they don't use the list field (or blocks field with the list block) in any of their blueprints, or if every user who can edit content is fully trusted. The attack only surfaces in the site frontend (i.e. in the consuming project's templates). The Panel itself is unaffected and will not execute JavaScript that was injected into list field content.
Introduction
Cross-site scripting (XSS) is a type of vulnerability that allows to execute 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 applications might have potential attackers in their group of authenticated Panel users. They can escalate their privileges if they get access to the Panel session of an admin user. Depending on the site, other JavaScript-powered attacks are possible.
A specific class of stored XSS is auto-firing, meaning the malicious injected JavaScript code is executed by the browser when the page loads without the victim having to perform a specific action.
Affected components
Kirby's list field stores its formatted content as HTML code. Unlike with other field types, it is not possible to escape HTML special characters against cross-site scripting (XSS) attacks, otherwise the formatting would be lost.
Impact
In affected releases, Kirby did not securely sanitize the contents of list fields on save. This allowed attackers to inject malicious HTML code into the content file by sending it to Kirby's API directly without using the Panel. This malicious HTML code would then be displayed on the site frontend and executed in the browsers of site visitors and logged in users who are browsing the site.
Patches
The problem has been patched in Kirby 4.9.1 and Kirby 5.4.1. Please update to one of these or a later version to fix the vulnerability.
In all of the mentioned releases, Kirby has added HTML sanitization (like in the writer field) to the backend code that handles updates to the contents of list fields.
Credits
Kirby thanks @offset for responsibly reporting the identified issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | getkirby/cms | all versions | 4.9.1 |
| 🐘Packagist | getkirby/cms | ≥ 5.0.0&&< 5.4.1 | 5.4.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getkirby/cms. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update getkirby/cms to 4.9.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-5fhx-9q32-q257 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-5fhx-9q32-q257 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-5fhx-9q32-q257. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-5fhx-9q32-q257 in your dependencies?
O3 detects GHSA-5fhx-9q32-q257 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.