getkirby Kirby up to 4.9.4/5.5.1 Media src/Filesystem/Dir.php realpath path traversal

Summaryinfo

A vulnerability, which was classified as critical, was found in getkirby Kirby up to 4.9.4/5.5.1. Affected is the function Kirby\Filesystem\Dir::realpath/Kirby\Filesystem\F::realpath of the file src/Filesystem/Dir.php of the component Media Handler. Executing a manipulation can lead to path traversal. This vulnerability is tracked as CVE-2026-75592. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability has been found in getkirby Kirby up to 4.9.4/5.5.1 and classified as critical. This vulnerability affects the function Kirby\Filesystem\Dir::realpath/Kirby\Filesystem\F::realpath of the file src/Filesystem/Dir.php of the component Media Handler. The manipulation with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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 used incomplete filesystem containment checks in src/Filesystem/Dir.php and src/Filesystem/F.php through Kirby\Filesystem\Dir::realpath() and Kirby\Filesystem\F::realpath(). The checks accepted a sibling directory whose path shared the intended root's string prefix, such as /var/www/site2 next to /var/www/site, because they did not require an exact match or a DIRECTORY_SEPARATOR boundary. A remote attacker could use Kirby\Cms\Media::thumb() to create and access thumbnails from image files in a PHP-readable sibling directory when that directory contained a valid .json thumbnail job file, potentially exposing staging sites, backups, or other internal sites and deleting the job file during processing. This issue is fixed in versions 4.9.5 and 5.5.2.

The advisory is available at github.com. This vulnerability was named CVE-2026-75592 since 08/18/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1006 by the MITRE ATT&CK project.

By approaching the search of inurl:src/Filesystem/Dir.php it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 4.9.5 or 5.5.2 eliminates this vulnerability.

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Productinfo

Vendor

• getkirby

Name

• Kirby

Version

• 4.9.0
• 4.9.1
• 4.9.2
• 4.9.3
• 4.9.4
• 5.5.0
• 5.5.1

Website

• Product: https://github.com/getkirby/kirby/

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