CVE-2020-26253 is a medium-severity (CVSS 5.9) CWE-346 vulnerability in getkirby/panel. O3 Security confirms whether CVE-2020-26253 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Kirby .dev domains and some reverse proxy setups were treated as local
Real-World Exposure
getkirby/panel🐘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
Kirby is a CMS. In Kirby CMS (getkirby/cms) before version 3.3.6, and Kirby Panel before version 2.5.14 there is a vulnerability in which the admin panel may be accessed if hosted on a .dev domain. In order to protect new installations on public servers that don't have an admin account for the Panel yet, we block account registration there by default. This is a security feature, which we implemented years ago in Kirby 2. It helps to avoid that you forget registering your first admin account on a public server. In this case – without our security block – someone else might theoretically be able to find your site, find out it's running on Kirby, find the Panel and then register the account first. It's an unlikely situation, but it's still a certain risk. To be able to register the first Panel account on a public server, you have to enforce the installer via a config setting. This helps to push all users to the best practice of registering your first Panel account on your local machine and upload it together with the rest of the site. This installation block implementation in Kirby versions before 3.3.6 still assumed that .dev domains are local domains, which is no longer true. In the meantime, those domains became publicly available. This means that our installation block is no longer working as expected if you use a .dev domain for your Kirby site. Additionally the local installation check may also fail if your site is behind a reverse proxy. You are only affected if you use a .dev domain or your site is behind a reverse proxy and you have not yet registered your first Panel account on the public server and someone finds your site and tries to login at yourdomain.dev/panel before you register your first account. You are not affected if you have already created one or multiple Panel accounts (no matter if on a .dev domain or behind a reverse proxy). The problem has been patched in Kirby 3.3.6. Please upgrade to this or a later version to fix the vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | getkirby/panel | all versions | 2.5.14 |
| 🐘Packagist | getkirby/cms | ≥ 3.0.0&&< 3.3.6 | 3.3.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getkirby/panel. 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/panel to 2.5.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-26253 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 CVE-2020-26253 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 CVE-2020-26253. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2020-26253 in your dependencies?
O3 detects CVE-2020-26253 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.