Plate: Media embed provider metadata can bypass URL sanitization and execute iframe JavaScript

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.7 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

EPSS

• CVE-2026-55596: 0.31% estimated exploitation activity in the next 30 days; percentile 23.52 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The media embed renderer trusts serialized provider or sourceUrl metadata and skips the URL protocol validation that normally blocks unsafe media embed URLs. A crafted Plate document can set a known video provider while keeping url as a javascript: iframe source. When a victim opens that document in an app using the registry media embed component, the component renders the attacker URL directly as an iframe src. Impact An attacker who can create or share Plate document content with another user can execute JavaScript in the victim browser context when the victim opens the document. This can expose application data available to the page and perform actions as the victim, depending on the host application's session model. Reproduction Use a Plate editor or viewer that renders media embeds with the registry MediaEmbedElement and load a document containing this node: When rendered, the node is treated as a Vimeo media embed because provider is present. The iframe receives the…

Published by the source

25 Aug 2026, 16:29 UTC

Last modified by the source

25 Aug 2026, 16:29 UTC

Source last checked

26 Oct 2026, 13:01 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-qj6x-xx2h-8hvv

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# Patch Next advisory brief: CVE-2026-55596

Advisory: Plate: Media embed provider metadata can bypass URL sanitization and execute iframe JavaScript
IDs: CVE-2026-55596, GHSA-qj6x-xx2h-8hvv
Record: https://patchnext.com/advisories/cve-2026-55596 (revision 1, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @platejs/media 53.1.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @platejs/media: affected >= 53.0.0, < 53.1.4; fixed in 53.1.4

## Suggested inspection (read-only)
- `npm ls @platejs/media --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## 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 @platejs/media.
- 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://github.com/advisories/GHSA-qj6x-xx2h-8hvv (GitHub-reviewed advisory GHSA-qj6x-xx2h-8hvv lists affected ranges: npm @platejs/media >=53.0.0 <53.1.4)

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