CVE-2026-44177 PoC — Kirby: Pre-authentication path traversal and PHP file inclusion during user lookup

Source

https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-44177.yaml

Associated Vulnerability

Title: Kirby: Pre-authentication path traversal and PHP file inclusion during user lookup (CVE-2026-44177)
Description:Kirby is an open-source content management system. In versions 5.3.0 and above but prior to 5.4.1, Kirby did not correctly validate the provided user ID, resulting in a path traversal vulnerability. Version 5.3.0 introduced a performance improvement to the Users collection that loaded user objects lazily when first needed. Users were queried by their ID, which was then used to locate the corresponding account directory under site/accounts. This affected the authentication API (accessible to unauthenticated requests), the users API (accessible only to authenticated users), and any other place that uses $users->find() to look up an individual user by a request-provided email or ID. As a result, an attacker could trigger arbitrary PHP file inclusion of files named index.php (for example, the main PHP files of plugins), the impact of which depends on the logic those files contain. It also allowed probing for the existence of arbitrary directories on the server, letting attackers fingerprint the server and site setup, including installed plugins and the content structure. This issue has been fixed in version 5.4.1.

Description

Kirby CMS versions 5.3.0 through 5.4.0 are vulnerable to a path traversal vulnerability via the /api/auth/login endpoint. An unauthenticated attacker may supply a specially crafted email value in the request body containing traversal sequences (such as "../.."), which the application concatenates directly into a filesystem path when hydrating user objects. This can result in the resolution of paths outside the intended accounts directory and may lead to the inclusion of unintended files such as index.php, causing a denial of service by exhausting memory limits. The issue is addressed in version 5.4.1 by properly validating and sanitizing the user-supplied input to prevent directory traversal.

File Snapshot

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