How severe is CVE-2020-26253?

CVE-2020-26253 has a CVSS score of 5.9/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-26253?

CVE-2020-26253 affects the following packages: getkirby/panel (Packagist), getkirby/cms (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2020-26253?

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.

How do I detect CVE-2020-26253 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getkirby/panel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2020-26253 if there is no patch (or I can't update yet)?

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.

Is CVE-2020-26253 actively exploited in the wild?

No public exploit code has been indexed for CVE-2020-26253 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2020-26253?

CVE-2020-26253 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 45th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-26253?

CVE-2020-26253 is classified as CWE-346 (CWE-346). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2020-26253 published, and has it been updated?

CVE-2020-26253 was published on December 8, 2020 and was last updated on August 27, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘

🐘 Packagist

Not in CISA KEV

MEDIUM severity

CVE-2020-26253 — panel

MEDIUMFix: getkirby-v2/panel@7f9ac18

CVE-2020-26253 is a medium-severity (CVSS 5.9) CWE-346 vulnerability in getkirby/panel. A fix is available for getkirby/panel — see the affected versions and patch details below.

Kirby .dev domains and some reverse proxy setups were treated as local

Also known asGHSA-2ccx-2gf3-8xvv

Published

Dec 8, 2020

Updated

Aug 27, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs45th percentile — riskier than 45% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2020-26253 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected

🐘getkirby/panel🐘getkirby/cms

Real-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

Impact

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/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).

Patches

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.

Workarounds

Kirby 2 sites on older releases can also be patched by applying the changes from this commit.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`getkirby/panel`	all versions	2.5.14`composer require getkirby/panel:^2.5.14`
🐘Packagist	`getkirby/cms`	≥ 3.0.0&&< 3.3.6	3.3.6`composer require getkirby/cms:^3.3.6`

Affected Products

2 products · 2 configurations

Application

kirbygetkirby

< 3.3.6

range

Application

panelgetkirby

< 2.5.14

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getkirby/panel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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.

Frequently Asked Questions

### Impact #### 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