Vulnerability · Published May 11, 2026 · Assigned by GitHub_M
CVE-2026-42845Grav: Anonymous Page Content Overwrite via Form File Upload filename Override
High 7.7
In plain English
A high-severity security flaw in grav-plugin-form from getgrav. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 55% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Packagist | getgrav/grav-plugin-form | 9.1.0 | GHSA-w4rc-p66m-x6qq |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| getgrav | grav-plugin-form | < 9.1.0 |
Weakness: CWE-73 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P