GHSA-8535-hvm8-2hmv — high GitHub Advisory (CVE-2025-66298) in composer/getgrav/grav

Description

Summary

Having a simple form on site can reveal the whole Grav configuration details (including plugin configuration details) by using the correct POST payload. Sensitive information may be contained in the configuration details.

PoC

Create a simple form with two fields, 'registration-number' and 'hp'. Add a submit button and set the method to POST(screenshot attached below). Form name set to 'hero-form'. Send a POST request with the following payload and you will notice a response with a php array listing the whole Grav configuration details - including plugins(screenshot attached).

registration-number:d643aaaa

hp:vJyifp

form-name:hero-form

unique_form_id:{{var_dump(_context|slice(0,7))}}

Screenshot 2025-03-25 at 7 26 02 AM

Screenshot 2025-03-25 at 7 22 58 AM

Impact

Server-Side Template (SST) vulnerability. The vulnerability affects the latest Grav version as of 25th of Match 2025 (1.7.48) with all plugins installed (including forms plugin v.7.4.2) to their latest versions as well.

Basic information

Type: reviewed
Severity: high
Advisory on GitHub: Open advisory ↗
Repository advisory: Open repository advisory ↗
Source code: Browse source ↗
Published (advisory): 2025-12-02 01:25:33 UTC
Updated: 2025-12-02 01:25:35 UTC
GitHub reviewed: 2025-12-02 01:25:33 UTC
NVD published: 2025-12-01

Score	Percentile
0.08%	22.93%

CVSS Scores

Base score	Version	Severity	Vector
7.7	4.0	—	`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:P` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network. Attack complexity (AC:L) Exploitation conditions are straightforward and stable. Attack requirements (AT:N) No additional preconditions are required beyond normal reachability. Privileges required (PR:N) No privileges are required. User interaction (UI:N) No user interaction is required. Vulnerable system confidentiality impact (VC:H) High confidentiality impact on the vulnerable system. Vulnerable system integrity impact (VI:N) No integrity impact on the vulnerable system. Vulnerable system availability impact (VA:N) No availability impact on the vulnerable system. Subsequent system confidentiality impact (SC:N) No confidentiality impact on subsequent systems. Subsequent system integrity impact (SI:N) No integrity impact on subsequent systems. Subsequent system availability impact (SA:N) No availability impact on subsequent systems. Exploit maturity (threat) (E:P) Proof-of-concept: public PoC exists; no reported exploitation and no known simplification tools.

Identifiers

Type	Value
GHSA	GHSA-8535-hvm8-2hmv ↗
CVE	CVE-2025-66298 ↗

CWEs

CWE id	Name
CWE-1336	Improper Neutralization of Special Elements Used in a Template Engine

Credits

yiannakasgeorge (reporter)

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem	Package	Vulnerable range	First patched	Vulnerable functions
composer	getgrav/grav	< 1.8.0-beta.27	1.8.0-beta.27	—

Grav is vulnerable to Server-Side Template Injection (SSTI) via Forms