CVE-2026-86197: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in getgrav grav
Description
Grav before 2.0.20 contains a cross-site scripting vulnerability in the Twig sandbox policy that allowlists addJs and addCss methods on Grav\Common\Assets without proper output escaping. Page editors can inject arbitrary script by registering malicious assets or injecting attributes, which are rendered unescaped into document head tags and executed for all visitors including administrators.
CVSS v4.0
Score 5.1medium
Affected software
getgrav
grav
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-86197 is a cross-site scripting vulnerability affecting Grav CMS versions prior to 2.0.20. The vulnerability arises from improper neutralization of input during web page generation in the Twig sandbox policy. Specifically, the addJs and addCss methods on Grav\Common\Assets are allowlisted but do not perform proper output escaping. This allows page editors to register malicious assets or inject attributes that are rendered unescaped into document head tags, leading to script execution in visitors' browsers.
Potential Impact
Successful exploitation allows an attacker with page editor privileges to inject arbitrary JavaScript that executes in the browsers of all site visitors, including administrators. This can lead to session hijacking, privilege escalation, or other malicious actions performed in the context of the affected website.
Mitigation Recommendations
A fix is available in Grav version 2.0.20. Users should upgrade to version 2.0.20 or later to remediate this vulnerability. No other mitigation guidance is provided in the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-09-05T11:52:36.821Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a9c0d23acd9273b49d9718b
Added to database: 09/05/2026, 12:37:55 UTC
Last enriched: 09/15/2026, 00:01:33 UTC
Last updated: 10/08/2026, 06:48:20 UTC
Views: 82
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