Description
TinaCMS registers window message listeners — the useTina overlay handler, the OAuth authentication popup handler, and the admin↔preview iframe GraphQL reducer — that act on event.data without verifying event.origin or event.source, and post messages using non-specific target origins.
Recommendation
Update the @tinacms/app package to the latest compatible version. Followings are version details:
- Affected version(s): < 2.5.6
- Patched version(s): 2.5.6
References
Could your website be exposed too?
SmartScanner can check your website for TinaCMS: Cross-origin postMessage handlers and rich-text URL-sanitization bypass enable stored XSS and session takeover - @tinacms/app and gives you actionable findings to investigate.
Start a free scanRelated Issues
- TinaCMS: Cross-origin postMessage handlers and rich-text URL-sanitization bypass enable stored XSS and session takeover - CVE-2026-55660
- TinaCMS rich-text (slatejson) rendering does not sanitize link/image URLs, allowing stored XSS via dangerous URL schemes - CVE-2026-55661
- TinaCMS rich-text (slatejson) rendering does not sanitize link/image URLs, allowing stored XSS via dangerous URL schemes - @tinacms/mdx - CVE-2026-55661
- TinyMCE Cross-Site Scripting (XSS) vulnerability using sanitization bypass through nested SVGs - CVE-2026-47760
You might also like:
See something that needs correcting? Let us knowUpdated June 19, 2026