Cross-site scripting from dynamic options in the multiselect fieldGHSA-3f89-869f-5w76
MEDIUMFix: getkirby/kirby@b5b8863GHSA-3f89-869f-5w76 is a medium-severity (CVSS 5.9) Cross-site Scripting (XSS) vulnerability in getkirby/cms. A fix is available for getkirby/cms — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- 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-3f89-869f-5w76.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
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
Introduction
Cross-site scripting (XSS) is a type of vulnerability that allows to execute any kind of JavaScript code inside the 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.
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. Depending on your site, other JavaScript-powered attacks are possible.
Impact
The multiselect field allows to select tags from an autocompleted list. Unfortunately, the Panel in Kirby 3.5 used HTML rendering for the raw option value.
This allowed attackers with influence on the options source (e.g. content of sibling pages or an API endpoint) to inject HTML code. If a page in the Panel that uses the manipulated multiselect options was visited by a victim and the victim opened the autocomplete dropdown, the victim's browser will then have rendered this malicious HTML code.
You are not affected by this vulnerability if you don't use the multiselect field or only use it with options that cannot be manipulated by attackers.
Patches
The problem has been patched in Kirby 3.5.8.1. Please update to this or a later version to fix the vulnerability.
Workarounds
We recommend to update to the patch release. If you cannot update immediately, you can work around the issue by disabling the multiselect field. This can be done by uncommenting this field from all your blueprints.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | getkirby/cms | all versions | 3.5.8.1composer require getkirby/cms:^3.5.8.1 |
Affected Products
kirbygetkirbyDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getkirby/cms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update getkirby/cms to 3.5.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3f89-869f-5w76 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is GHSA-3f89-869f-5w76 in your dependencies?
Find it across Packagist, including transitive dependencies.