# CVE-2026-54003: Kirby: External Initialization of the Panel on reverse proxy setups with the `Forwarded` header

> Attackers can bypass local IP checks via spoofed headers to install the Panel and create an admin account on unconfigured Kirby sites behind reverse proxies.

- **Severity:** Critical 9.1 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Jul 2026
- **Updated:** 9 Jul 2026
- **Also known as:** GHSA-whxw-24jc-cwmv

## What is CVE-2026-54003?

CVE-2026-54003 is a critical authentication bypass vulnerability in getkirby kirby, published on 9 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Kirby is an open-source content management system. Prior to 4.9.4 and from 5.4.4, Kirby sites with no configured user accounts that run on publicly accessible servers behind a reverse proxy setting the Forwarded, X-Client-IP, or X-Real-IP request header could allow remote attackers to install the Panel and create the first admin user because local-IP checks trusted those headers incorrectly. This issue is fixed in versions 4.9.4 and 5.4.4.

Weakness: CWE-454 (External Initialization of Trusted Variables or Data Stores)

## Which versions are affected by CVE-2026-54003?

4 open source packages ship an affected version, including getkirby/cms.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `getkirby/cms` | Packagist | All versions | 4.9.4 |
| `getkirby/cms` | Packagist | All versions | 4.9.4 |
| `getkirby/cms` | Packagist | From 5.0.0-alpha.1 | 5.4.4 |
| `getkirby/cms` | Packagist | From 5.0.0-alpha.1 | 5.4.4 |

## How do I fix CVE-2026-54003?

Upgrade getkirby/cms to a fixed version for your release line: 4.9.4 or 5.4.4.

## Is CVE-2026-54003 being exploited?

There is no known exploitation of CVE-2026-54003 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54003 and fix it if it is affected.

What it is: CVE-2026-54003 is a critical authentication bypass vulnerability in getkirby kirby, published on 9 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-54003 in the wild and no public exploit code.

Affected packages and fixed versions:
- getkirby/cms (Packagist): affected all versions; fixed in 4.9.4
- getkirby/cms (Packagist): affected all versions; fixed in 4.9.4
- getkirby/cms (Packagist): affected from 5.0.0-alpha.1; fixed in 5.4.4
- getkirby/cms (Packagist): affected from 5.0.0-alpha.1; fixed in 5.4.4

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-54003/ (Markdown: https://insights.sbomify.com/CVE-2026-54003/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54003
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54003
- OSV: https://osv.dev/vulnerability/CVE-2026-54003

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54003/
Summaries are generated and may contain mistakes; the official description above is the record.