CVE-2026-42845: Getgrav Grav-Plugin-Form

High severity, CVSS 7.7. EPSS: 0.4% chance of exploitation in the next 30 days.

The form plugin for Grav adds the ability to create and use forms. Prior to 9.1.0 , there is an unauthenticated page-content overwrite via file upload (GHSA-w4rc-p66m-x6qq). Public form uploads now strip path components from the POST-supplied filename and hard-block page-content extensions (`md`, `yaml`, `yml`, `json`, `twig`, `ini`) regardless of the configurable dangerous-extensions list. A permissive `accept` policy combined with the default `destination: self@` could otherwise let an attacker overwrite the page's own `.md` and pivot to super-admin via a `process: save` action. This vulnerability is fixed in 9.1.0.

Affected products

• Getgrav Grav-Plugin-Form: before 9.1.0 (fixed in 9.1.0)

Published 2026-05-11. Last modified 2026-06-17.