CVE-2026-44177: Kirby is an open-source content management system.

Kirby is an open-source content management system.

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 from the National Vulnerability Database, published by GitHub

What it means for a small business

If your business uses kirby, install the vendor's update. If you're not sure whether you use it, ask whoever manages your computers.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 1.8%, higher than 78% of CVEs. That’s above average: worth scheduling this week. Scored October 28, 2026, updated daily.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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