CVE-2026-42844: Grav privilege escalation via arbitrary file upload in blueprint-upload API

CVE-2026-42844 · Severity: high · CVSS 8.8 · Published 2026-05-12

Grav is a file-based content management system (CMS) used to build and manage websites. A security flaw in its API allows a user with limited permissions to upload a specially crafted file that creates a new administrative account. An attacker can use this new account to take full control of the website, including modifying content, changing configurations, and managing other users.

Technologies: Grav, getgrav/grav (Packagist). Vendors: Grav, Packagist.

Quick answers

Is CVE-2026-42844 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-42844 being exploited in the wild.
How severe is CVE-2026-42844?
High severity, with a CVSS score of 8.8, published 12 May 2026.
Which products and versions are affected?
Grav < 2.0.0-beta.4, 2.0.0-beta.2; getgrav/grav (Packagist) < 2.0.0-beta.4, ECOSYSTEM:introduced=0,fixed=2.0.0-beta.4.
Is there a fix for CVE-2026-42844?
Yes. getgrav/grav (Packagist): upgrade to 2.0.0-beta.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-42844 attacked?
It is attacked over the network, in a web application.
Am I affected by CVE-2026-42844?
Check whether you run Grav or getgrav/grav (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • getgrav/grav (Packagist): upgrade to 2.0.0-beta.4 or later
    composer require getgrav/grav:^2.0.0-beta.4

Technical details

An authenticated vertical privilege escalation vulnerability exists in Grav 2.0.0-beta.2 due to improper path validation in the '/api/v1/blueprint-upload' endpoint. By manipulating the 'destination' and 'scope' parameters, an attacker with 'api.media.write' permissions can bypass intended directory restrictions to write arbitrary YAML files into the 'user/accounts/' directory. Since Grav uses these YAML files for user authentication and supports plaintext passwords for initial logins, an attacker can plant a new user file with 'api.super' privileges. This allows the attacker to log in as a super-administrator, resulting in full compromise of the Grav API and the underlying CMS. The issue is fixed in API version 1.0.0-beta.17.

Affected products

  • getgrav Grav 2.0.0-beta.2

Identifiers

  • CVE-2026-42844
  • GHSA-6xx2-m8wv-756h

Timeline

  • 2026-04-28: advisory: GitHub Security Advisory published by vendor
  • 2026-05-12: disclosed: CVE published to NVD

References

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