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Medium, CVSS 5.1amended

Grav: Page editors can inject arbitrary script into rendered pages via the Twig sandbox's assets.addJs/addCss allowlist, escalating to super-admin

CVE-2026-86197GHSA-8hgv-xc77-jmcr

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (getgrav/grav 2.0.20), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
5.1 · 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 · score source
EPSS
  • CVE-2026-86197: 0.41% estimated exploitation activity in the next 30 days; percentile 35.49 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary Grav 2.0 renders editor-authored Twig in page content by default and relies on the Twig content sandbox to contain it. The shipped sandbox policy allowlists addcss and addjs on Grav\Common\Assets (system/src/Grav/Common/Twig/Sandbox/SandboxDefaults.php:307). Because the sandbox arbitrates the call and not its downstream effect, a user holding only page-edit rights can register an arbitrary asset from page content; the theme then emits it into the document head as a <script src / <link href tag. The asset URL is concatenated into that tag without escaping, so it can also break out of its own attribute. The save-time XSS scan cannot see this: Security::detectXssInEditorContent() renders the content body in isolation and inspects the returned string, while assets.addJs() acts by mutating the shared Assets service and returns only an object key. The payload contains no markup for the scanner to flag. This is not a Security::detectXss() bypass. It is content reaching an unescaped…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-8hgv-xc77-jmcr

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GHSA-8hgv-xc77-jmcr

Agent brief

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# Patch Next advisory brief: CVE-2026-86197

Advisory: Grav: Page editors can inject arbitrary script into rendered pages via the Twig sandbox's assets.addJs/addCss allowlist, escalating to super-admin
IDs: CVE-2026-86197, GHSA-8hgv-xc77-jmcr
Record: https://patchnext.com/advisories/cve-2026-86197 (revision 3, source checked 26 Oct 2026, 14:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: getgrav/grav 2.0.20. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist getgrav/grav: affected <= 2.0.19; fixed in 2.0.20

## Suggested inspection (read-only)
- Packagist getgrav/grav: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on getgrav/grav.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-8hgv-xc77-jmcr (OSV record GHSA-8hgv-xc77-jmcr lists affected ranges: Packagist getgrav/grav >=0 <2.0.20 (fixed))
- Verified: https://github.com/advisories/GHSA-8hgv-xc77-jmcr (GitHub-reviewed advisory GHSA-8hgv-xc77-jmcr lists affected ranges: Packagist getgrav/grav >=0 <=2.0.19)

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