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

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Plate is a rich-text editor with AI and shadcn/ui. From 53.0.0 until 53.1.4, the media embed renderer trusts serialized provider or sourceUrl metadata in useMediaState and skips parseMediaUrl protocol validation, allowing a crafted Plate document to set a known video provider while keeping url as a javascript: iframe source that the registry MediaEmbedElement renders directly as an iframe src when a victim opens the document. This issue is fixed in version 53.1.4.

Source published

8 Jul 2026 20:27:58 UTC

Source modified

9 Jul 2026 13:41:00 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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

Plate is a rich-text editor with AI and shadcn/ui. From 53.0.0 until 53.1.4, the media embed renderer trusts serialized provider or sourceUrl metadata in useMediaState and skips parseMediaUrl protocol validation, allowing a crafted Plate document to set a known video provider while keeping url as a javascript: iframe source that the registry MediaEmbedElement renders directly as an iframe src when a victim opens the document. This issue is fixed in version 53.1.4.

Source published

Jul 8, 2026, 8:27:58 PM (timezone not stated)

Source modified

Jul 9, 2026, 1:41:00 PM (timezone not stated)

Observed here

7 Nov 2026 12:32:37 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

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

Plate is a rich-text editor with AI and shadcn/ui. From 53.0.0 until 53.1.4, the media embed renderer trusts serialized provider or sourceUrl metadata in useMediaState and skips parseMediaUrl protocol validation, allowing a crafted Plate document to set a known video provider while keeping url as a javascript: iframe source that the registry MediaEmbedElement renders directly as an iframe src when a victim opens the document. This issue is fixed in version 53.1.4.

Source published

8 Jul 2026 21:16:50 UTC

Source modified

25 Oct 2026 17:10:00 UTC

Observed here

27 Oct 2026 15:15:14 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 8.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

## 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: ```json { "type": "media_embed", "provider": "vimeo", "sourceUrl": "https://vimeo.com/1", "url": "javascript:parent.postMessage('plate-media-xss','*')", "children": [{ "text": "" }] } ``` When rendered, the node is treated as a Vimeo media embed because `provider` is present. The iframe receives the unvalidated `url` value as its `src`. ## Root Cause / Technical Details `parseMediaUrl` is the intended hardening point for media embed URLs and rejects parser output unless the URL protocol is `http:` or `https:`. However, `useMediaState` had a fast path for serialized nodes that already contain `provider` or `sourceUrl`. That fast path returned `{ id, provider, sourceUrl, url }` directly and did not call `parseMediaUrl` or otherwise validate the stored `url`. The registry `MediaEmbedElement` then checks that `embed.provider` is one of the video providers and renders non-YouTube video providers with `<iframe src={embed.url}>`. Because `provider` is attacker-controlled serialized document metadata, it can be set to `vimeo` while `url` remains `javascript:...`. This is fixed in `@platejs/media` 53.1.4 by recomputing embed metadata from the render URL instead of trusting serialized `provider`, `id`, or `sourceUrl` metadata. ## PoC Evidence A browser proof using the same data flow set an iframe `src` to: ```text javascript:parent.postMessage('plate-media-xss','*') ``` Chromium executed the iframe JavaScript and the parent page received `plate-media-xss`, confirming execution from the iframe source. ## Remediation Upgrade `@platejs/media` to 53.1.4 or later. Treat `provider`, `sourceUrl`, and `id` in serialized documents as untrusted derived metadata. Recompute embed metadata from `url` with `parseMediaUrl`, or at minimum validate any fast-path `url` with the same protocol allowlist before rendering an iframe.

Source published

25 Aug 2026 16:29:25 UTC

Source modified

26 Aug 2026 00:40:54 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

Publisher rating · HIGH