GHSA-gqxx-248x-g29f Grav Admin Plugin vulnerable to Cross-Site Scripting (XSS) Stored endpoint `/admin/config/site` parameter `data[taxonomies]`

• Packagist getgrav/grav: < 1.8.0-beta.27 → fixed in 1.8.0-beta.27

Summary A Stored Cross-Site Scripting (XSS) vulnerability was identified in the `/admin/config/site` endpoint of the _Grav_ application. This vulnerability allows attackers to inject malicious scripts into the `data[taxonomies]` parameter. The injected payload is stored on the server and automatically executed in the browser of any user who accesses the affected site configuration, resulting in a persistent attack vector. --- Details Vulnerable Endpoint: `POST /admin/config/site` Parameter: `data[taxonomies]` The application does not properly validate or sanitize input in the `data[taxonomies]` field. As a result, an attacker can inject JavaScript code, which is stored in the site configuration and later rendered in the administrative interface or site output, causing automatic execution in the user's browser. --- PoC Payload: `">alert('XSS-PoC')` Steps to Reproduce: 1. Log in to the _Grav_ Admin Panel with sufficient permissions to modify site configuration. 2. Navigate to Configuration > Site. 3. In the Taxonomies Types field (which maps to `data[taxonomies]`), insert the payload above: `">alert('XSS-PoC')` 4. Save the configuration. 5. Go on Pages and click on one of them 6. The stored payload is executed immediately in the browser, confirming the Stored XSS vulnerability. 7. The HTTP request submitted during this process contains the vulnerable parameter and payload: --- Impact Stored XSS attacks can lead to severe consequences, including: • Session hijacking: Stealing cookies or authentication tokens to impersonate users • Credential theft: Harvesting usernames and passwords using malicious scripts • Malware delivery: Distributing unwanted or harmful code to victims • Privilege escalation: Compromising administrative users through persistent scripts • Data manipulation or defacement: Changing or disrupting site content • Reputation damage: Eroding trust among site users and administrators --- Discoverer Marcelo Queiroz by CVE-Hunters