PT-2026-38283 · Grav · Grav-Plugin-Form

Fr0Stydev · Published 2026-05-06 · Updated 2026-05-11 · CVE-2026-42845

Positive Technologies (AI Summary)

CVSS v4.0

8.7

High

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Name of the Vulnerable Software and Affected Versions Grav form plugin versions prior to 9.1.0

Description An unauthenticated page-content overwrite exists via file upload. The file upload handler in user/plugins/form/classes/Form.php uses a filename parameter that can be controlled via POST requests. Because the Utils::checkFilename() function only blocks a limited set of extensions, files with extensions such as .md are permitted. When a form is configured with a permissive accept policy and the default destination: self@ setting, an attacker can upload a malicious markdown file to overwrite the page's own content file. This can be leveraged to pivot to super-admin privileges by utilizing a process: save action.

Recommendations Update the form plugin to version 9.1.0. As a temporary workaround, restrict the accept policy of file upload fields to exclude text-based extensions or avoid using the destination: self@ configuration.

Exploit

Fix

RCE

Weakness Enumeration

CWE-73

CWE-20

Related Identifiers

CVE-2026-42845

GHSA-W4RC-P66M-X6QQ

Affected Products

Grav-Plugin-Form

References · 6

• 🔥 https://github.com/getgrav/grav/security/advisories/GHSA-w4rc-p66m-x6qq · Exploit
• https://osv.dev/vulnerability/GHSA-w4rc-p66m-x6qq · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-42845 · Security Note
• https://github.com/getgrav/grav · Note
• https://github.com/getgrav/grav-plugin-form/commit/48bacc4187e1cff815000e526d5ca2878484867f · Note
• https://twitter.com/CVEnew/status/2053932462418657604 · Twitter Post