Summary
Kirby .dev domains and some reverse proxy setups were treated as local
About our registration block
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.
The issue
As noted by Jukka Rautanen, 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.
In fixing this issue, we've also found out that the local installation check may also fail if your site is behind a reverse proxy.
Am I affected?
You are only affected if:
- you use a .dev domain or your site is behind a reverse proxy &
- you have not yet registered your first Panel account on the public server &
- someone finds your site and tries to login at
yourdomain.dev/panelbefore 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).
Workarounds
Kirby 2 sites on older releases can also be patched by applying the changes from this commit.
Impact
CVE-2020-26253 has a CVSS score of 6.8 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.5.14, 3.3.6); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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The problem has been patched in Kirby 2.5.14 and Kirby 3.3.6. Please update to one of these or a later version to fix the vulnerability.
Note: Kirby 2 reaches end of life on December 31, 2020. We therefore recommend to upgrade your Kirby 2 sites to Kirby 3. If you cannot upgrade, we still recommend to update to Kirby 2.5.14.
Frequently Asked Questions
- What is CVE-2020-26253? CVE-2020-26253 is a medium-severity security vulnerability in getkirby/panel (composer), affecting versions < 2.5.14. It is fixed in 2.5.14, 3.3.6.
- How severe is CVE-2020-26253? CVE-2020-26253 has a CVSS score of 6.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which packages are affected by CVE-2020-26253?
getkirby/panel(composer) (versions < 2.5.14)getkirby/cms(composer) (versions >= 3.0.0, < 3.3.6)
- Is there a fix for CVE-2020-26253? Yes. CVE-2020-26253 is fixed in 2.5.14, 3.3.6. Upgrade to this version or later.
- Is CVE-2020-26253 exploitable, and should I be worried? Whether CVE-2020-26253 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2020-26253 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2020-26253?
- Upgrade
getkirby/panelto 2.5.14 or later - Upgrade
getkirby/cmsto 3.3.6 or later
- Upgrade