CVE-2026-55660High▾ TwilightTinaCMS: Cross-origin postMessage handlers and rich-text URL-sanitization bypass enable stored XSS and session takeover
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Jul 4.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via GHSA
0.2%
0.2% → 0.3%
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. A page the victim visits (or a window in an opener/iframe relationship with a Tina admin) can forge messages to drive the editor, inject preview content, or observe/forge the OAuth popup channel to take over an authenticated editing session.
Fixed in #7056 by allow-listing trusted origins and verifying event.source (isFromAdmin, isFromTrustedPreviewOrigin), and by posting only to explicit target origins (never "*").
Note: the rich-text URL-sanitization issue previously bundled here has been split into its own advisory (GHSA-2vcc-5v34-9jc8) so each vulnerability can receive a distinct CVE.
tinacms < 3.9.3@tinacms/app < 2.5.6Upgrade to a patched release:
tinacms 3.9.3@tinacms/app 2.5.6Connected by shared product, vendor, weakness, or advisory.
CVE-2026-55661MediumTinaCMS rich-text (slatejson) rendering does not sanitize link/image URLs, allowing stored XSS via dangerous URL schemes
CVE-2026-63506High· 8.8Tina is a headless content management system
CVE-2026-55087Medium· 6.1Etherpad is a real-time collaborative editor
CVE-2026-53668Medium· 6.9React Router: Open redirect leading to XSS
GHSA-x445-f3h2-j279Medium· 6.8Auth.js: OAuth state, nonce, and PKCE check cookies are not bound to the provider that created them
CVE-2026-48022Medium· 6.5@hapi/wreck: Sensitive credential headers leak across cross-port and cross-scheme redirects