---
id: CVE-2026-75594
title: Kirby is an open-source content management system
summary: >-
  Kirby is an open-source content management system. Prior to 4.9.5 and 5.5.2,
  depending on the release line, Kirby's media handler in src/Cms/Media.php
  allowed Kirby\Cms\Media::thumb() to append a path-bearing filename to a
  validated pare…
severity: high
cwe:
  - CWE-22
vendor: getkirby
product: getkirby/cms
affected:
  - getkirby/cms <= 4.9.4
  - 'getkirby/cms >= 5.0.0, < 5.5.2'
patched:
  - getkirby/cms 4.9.5
  - getkirby/cms 5.5.2
published: '2026-08-31'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T21:11:31.703'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-75594'
references:
  - url: >-
      https://github.com/getkirby/kirby/commit/22fbaedb7e6dd61f5def10829ba7bd7e73e0dcc9
    label: security-advisories@github.com
  - url: >-
      https://github.com/getkirby/kirby/commit/a40808f5c2ee5d42bb597fb6ffbe0de0ce8e4d20
    label: security-advisories@github.com
  - url: >-
      https://github.com/getkirby/kirby/commit/cd7abb68d298f3443eafd43fa2d0c7ad0f933d0e
    label: security-advisories@github.com
  - url: >-
      https://github.com/getkirby/kirby/commit/e0dca5f709adc21b36f5549df2c0619bc59da56c
    label: security-advisories@github.com
  - url: 'https://github.com/getkirby/kirby/releases/tag/4.9.5'
    label: security-advisories@github.com
  - url: 'https://github.com/getkirby/kirby/releases/tag/5.5.2'
    label: security-advisories@github.com
  - url: 'https://github.com/getkirby/kirby/security/advisories/GHSA-9vx2-j98c-p72w'
    label: security-advisories@github.com
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-75594'
  - url: 'https://github.com/advisories/GHSA-9vx2-j98c-p72w'
tags:
  - nvd
  - ghsa
  - composer
epss: 0.00513
epssPercentile: 0.42557
aliases:
  - GHSA-9vx2-j98c-p72w
ecosystem: composer
ingestedAt: '2026-08-31T22:14:59.068Z'
---

## Overview

Kirby is an open-source content management system. Prior to 4.9.5 and 5.5.2, depending on the release line, Kirby's media handler in src/Cms/Media.php allowed Kirby\Cms\Media::thumb() to append a path-bearing filename to a validated parent media directory. On nginx, PHP's built-in server, or Apache with AllowEncodedSlashes enabled, a remote attacker could submit encoded slash characters such as %2f in the filename and traverse outside the parent's media directory. Differences between responses for existing and nonexistent thumbnail configurations disclosed whether an arbitrary .json file existed, and a .json file containing a valid filename key could cause the referenced image to be returned and the job file to be deleted. The related file::version path in src/Filesystem/Asset.php also accepted ../ sequences outside the intended index root. This issue is fixed in versions 4.9.5 and 5.5.2.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-75594)

Affected packages:

- `getkirby/cms <= 4.9.4`
- `getkirby/cms >= 5.0.0, < 5.5.2`

Patched in:

- `getkirby/cms 4.9.5`
- `getkirby/cms 5.5.2`

Source: https://github.com/advisories/GHSA-9vx2-j98c-p72w