Is CVE-2026-54003 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-54003 being exploited in the wild.

How severe is CVE-2026-54003?

Critical severity, with a CVSS score of 4, published 9 July 2026.

Which products and versions are affected?

Kirby = 5.0.0, < 5.4.4, <= 4.9.3, 5.0.0-alpha.1 to 5.4.3; getkirby/cms (Packagist) ECOSYSTEM:introduced=0,fixed=4.9.4.

Is there a fix for CVE-2026-54003?

Yes. getkirby/cms (Packagist): upgrade to 4.9.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-54003 attacked?

It is attacked over the network, in a web application.

Am I affected by CVE-2026-54003?

Check whether you run Kirby or getkirby/cms (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-54003: Kirby CMS authentication bypass in Panel installation via header spoofing

Q: Which products and versions are affected?

Kirby = 5.0.0, < 5.4.4, <= 4.9.3, 5.0.0-alpha.1 to 5.4.3; getkirby/cms (Packagist) ECOSYSTEM:introduced=0,fixed=4.9.4.

Q: Is there a fix for CVE-2026-54003?

Yes. getkirby/cms (Packagist): upgrade to 4.9.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-54003 attacked?

It is attacked over the network, in a web application.

Q: Am I affected by CVE-2026-54003?

Check whether you run Kirby or getkirby/cms (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-54003 · Severity: critical · CVSS 4 · Published 2026-07-09

Kirby is a content management system used to build and manage websites. A vulnerability exists where new installations or sites without existing user accounts can be hijacked by remote attackers. If the server is behind certain network configurations, an attacker can bypass security checks to access the setup panel and create an administrative account, effectively taking full control of the website.

Technologies: Kirby, getkirby/cms (Packagist). Vendors: Kirby, Packagist.

Quick answers

Is CVE-2026-54003 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-54003 being exploited in the wild.
How severe is CVE-2026-54003?: Critical severity, with a CVSS score of 4, published 9 July 2026.
Which products and versions are affected?: Kirby < 4.9.4, >= 5.0.0, < 5.4.4, <= 4.9.3, 5.0.0-alpha.1 to 5.4.3; getkirby/cms (Packagist) ECOSYSTEM:introduced=0,fixed=4.9.4.
Is there a fix for CVE-2026-54003?: Yes. getkirby/cms (Packagist): upgrade to 4.9.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-54003 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-54003?: Check whether you run Kirby or getkirby/cms (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

getkirby/cms (Packagist): upgrade to 4.9.4 or later
```
composer require getkirby/cms:^4.9.4
```

Technical details

A vulnerability in Kirby's `isLocal()` check in the `Http\Environment` component incorrectly trusts several HTTP request headers, including `Forwarded`, `X-Client-IP`, and `X-Real-IP`. On sites with no configured user accounts, Kirby allows administrative Panel installation if the request appears to originate from a local IP. An attacker can spoof these headers to bypass the local-IP restriction when the site is hosted behind a reverse proxy that passes these headers. This allows the attacker to create the initial admin user and gain full control of the CMS. The issue is fixed in versions 4.9.4 and 5.4.4.

Affected products

getkirby Kirby < 4.9.4, >= 5.0.0, < 5.4.4

Identifiers

CVE-2026-54003
GHSA-whxw-24jc-cwmv

Timeline

2026-05-28: patched: Fix merged into development branch
2026-06-17: advisory: Security releases 4.9.4 and 5.4.4 published
2026-07-09: disclosed: CVE-2026-54003 published

References

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