GHSA-3f89-869f-5w76
MEDIUMCross-site scripting from dynamic options in the multiselect field
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.
Blast Radius
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 | 3.5.8.1 |
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 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
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-3f89-869f-5w76 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-3f89-869f-5w76. 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-3f89-869f-5w76 in your dependencies?
O3 detects GHSA-3f89-869f-5w76 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.