CVE-2026-44177

Received Received - Intake

Path Traversal in Kirby CMS

Publication date: 2026-07-16

Last updated on: 2026-07-16

Assigner: GitHub, Inc.

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.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-07-16

Last Modified

2026-07-16

Generated

2026-07-17

AI Q&A

2026-07-17

EPSS Evaluated

N/A

NVD

CVE-2026-44177

Affected Vendors & Products

Vendor	Product	Version / Range
kirby	kirby	to 5.4.1 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-98	The PHP application receives input from an upstream component, but it does not restrict or incorrectly restricts the input before its usage in "require," "include," or similar functions.
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.

Attack-Flow Graph

Executive Summary

Kirby CMS versions 5.3.0 to 5.4.0 had a path traversal flaw due to improper user ID validation. The system allowed lazy loading of user objects by ID, which could be manipulated to access arbitrary directories or include PHP files like plugin index.php files. This affected authentication and users APIs.

Detection Guidance

Check Kirby CMS version. If running 5.3.0 or higher but below 5.4.1, the system is vulnerable. Inspect site/accounts directory for unexpected PHP file inclusions or directory probing attempts.

Impact Analysis

An attacker could exploit this to include malicious PHP files, potentially executing arbitrary code on the server. They could also probe for directories to identify installed plugins or site structure, aiding further attacks.

Mitigation Strategies

Upgrade Kirby CMS to version 5.4.1 or later immediately. Review logs for unauthorized access or file inclusion attempts. Restrict access to the authentication and users API endpoints.

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