fkie_cve-2026-108261

Tina is a headless content management system. Prior to tinacms 3.14.0 and @tinacms/app 2.5.14, the /~/* admin preview route in packages/tinacms/src/admin/index.tsx can turn an attacker-controlled hash-router splat into an off-origin iframe URL through packages/@tinacms/app/src/preview.tsx, while packages/@tinacms/app/src/lib/preview-origin.ts derives expectedOrigin from that same URL for the GraphQL message channel in packages/@tinacms/app/src/lib/graphql-reducer.ts. An unauthenticated attacker can send a crafted link to a signed-in editor, cause the admin to frame an attacker origin, and have that frame treated as the trusted preview. The attacker-controlled frame can submit GraphQL reads or mutations that the admin executes with the editor credentials, exposing or modifying protected content. This issue is fixed in tinacms 3.14.0 and @tinacms/app 2.5.14.

GHSA-x34j-47hf-4xg7 — TinaCMS admin preview iframe loads an attacker-controlled origin from the URL fragment

Affected: npm: tinacms, npm: @tinacms/app

### Summary

The TinaCMS admin builds its preview `<iframe src>` from the `/~/*` hash-router splat without checking that the value stays same-origin. A fragment with a doubled slash (`#/~//attacker.example/p`) becomes the protocol-relative URL `//attacker.example/p`, so the admin frames an external site. That same unvalidated string derives `expectedOrigin`, the only trust anchor for the admin↔preview `postMessage` channel, so the attacker's frame is treated as trusted: it can submit any GraphQL operation, which the admin executes with the signed-in editor's token and posts back to the attacker's origin.

One link, opened by a logged-in editor, gives an unauthenticated remote attacker arbitrary read and write access to the site's content API as that editor.

### Details

Root cause — the router splat becomes the frame source with no same-origin check:

``` packages/tinacms/src/admin/index.tsx:16 HashRouter as Router, packages/tinacms/src/admin/index.tsx:329 path='/~/*' packages/tinacms/src/admin/index.tsx:173 const [url, setURL] = React.useState(`/${params['*']}`); packages/tinacms/src/admin/index.tsx:176 const paramURL = `/${params['*']}`; packages/@tinacms/app/src/preview.tsx:24 src={props.url} ```

The leading `/` is meant to force a relative path, but `react-router-dom@6.30.3` returns the splat with its own leading slash for `/~//x`, producing `//x`. The iframe has no `sandbox` attribute and the admin bundle ships no CSP.

The trust anchor is then c…

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fkie_cve-2026-108261

GHSA-x34j-47hf-4xg7 — TinaCMS admin preview iframe loads an attacker-controlled origin from the URL fragment